I'm gonna be a right boring cnut and do my own...though I've only gone back to 97 as before that I was a small child with child like memories and opinions. I could probably do 96 but I got lazy:
1997
Teddy Sheringham - 8 Berbatime can travel backwards, where it's more affordable and cost effecient
Erik Nevland - 5 Years after leaving, single handedly knocked Chelsea out of Europe whilst playing for some weird team. Strangely, I remember him as a United player purely because I can't remember him as a United player.
Henning Berg - 7 The master of miraculous goal line clearances
1998
Jonathan Greening - 5 Unpleasantly surprised to learn we actually paid money for him
Jaap Stam - 8 Brilliant defender with a brilliantly amusing looking head.
Jesper Blomqvist - 6 Signed as some form of inferior Ryan Giggs, which he was, in the same way a marble may be seen as an inferior version of a planet.
Dwight Yorke - 7 I remember us signing him and deciding he was good based on the fact we signed him. Turns out this was correct.
1999
Mark Bosnich - 4 A clown
Quinton Fortune - 7 I liked his angry smiling face. Decent pretend fullback. Decent back up midfielder.
Massimo Taibi - 3 Man Of The Match against Liverpool at Anfield
Mikael Silvestre - 7 Diagonal balls, calamaty defending, wasting last chance to get back into game with trademark 50 yard shot. Despite this, was quite good somehow.
Bojan Djordjic - 5 I remember him. He'd appear on Manchester United's squad list on every computer game for about 5 years, but I never got confirmation that he existed in real life.
2000
Fabien Barthez - 6 The Deportivo game STILL infuriates me. WHY did he suddenly just run into the middle of the pitch and then stand there?
2001
Ruud van Nistelrooy - 9 Only scored tap ins...except for when he didn't. Didn't do much else though, mainly due to most of his time being taken up by the amount of tap ins he scored.
Juan Veron - 5 Made sense as a signing, easily had the quality and flair...did things like miss half a season because his toe hurt.
Roy Carroll - 6 Decent back up. Annoying habit of occasionally throwing ball into own net.
Laurent Blanc - 2 The justification for signing him seems to be that he used to be good once so it didn't matter if he couldn't run anymore. Would probably play in midfield if he was still here now.
Kieran Richardson - 5 One of the original players who Fergie would put in midfield when he didn't particularly fancy having an actual midfield.
2002
Diego Forlan - 7 Whenever he scored it was the greatest thing ever.
Rio Ferdinand - 9 Started to take himself seriously after getting himself banned for nearly an entire year. Now combines being a feckwit with being a strangely admirable character.
Luke Steele - 5 Not much you can say about a reserve goalkeepr signed at a time when we had 4 first team goalkeepers.
Ricardo Lopez - 4 Brought on whenever we desperately needed to concede a penalty
2003
David Bellion - 5 MEN seem to think we signed him from some French team? Fairly sure we stole him from Sunderland who were just pretending they still wanted him.
Eric Djemba-Djemba - 3 Went downhill after he came on in the Charity Shield and started kicking Arsenal players everywhere. In hindsight, he probably was actually aiming for the ball.
Tim Howard - 6 Looked the business, then fumbled a cross or something and proceeded to never play well again.
Cristiano Ronaldo - 10 One trick pony who should be sold and then beheaded by Wayne Rooney.
Kleberson - 5 Mastered the art of being useless at football by being really good at it. Should have signed for Arsenal
Lee Martin - 5 Is this the one who looked shit hot in the reserves, but then each year, he'd spend the next year looking shit hot in the reserves, and then eventually he was too old? If so, him.
2004
Dong - 1 Probably sold some shirts somewhere, or something.
Louis Saha - 7 Didier Drogba if he actually was always injured instead of just pretending to be.
Alan Smith - 7 Decent as a striker. So bad at being the new Roy Keane that the old Roy keane went mad and was booted out of the club.
Gabriel Heinze - 6 Maniacle defender who couldn't defend and then demanded the right to play for Liverpool
Liam Miller - 4 Last seen in a Celtic shirt, single handedly outplaying Barcelona's entire midfield at the Nou Camp.
Wayne Rooney - 8 Would be higher, but it was just the most obvious Manchester United signing ever.
Florent N’Galula - n/a I only remember him because he had a funny name
2005
Nemanja Vidic - 9 I didn't know who he was
Patrice Evra - 9 I knew who he was, but I thought he was shit.
Edwin van der Sar - 8 Strangely obvious signing.
Park Ji-Sung - 8 One of those Fergie signings where no one else would think to bring him in, but Fergie does and turns him into a vitally important player, despite no one really being sure what he's good at.
Ben Foster - 6 England's new no1.
2006
Michael Carrick - 9 Disliked signing by many at time due to not being Roy Keane. Then it turned out signing him meant Manchester United had a midfield again. Now, him and Manchester United's entire midfield are literally the same thing.
2007
Owen Hargreaves - 4 Extremely large fee paid for man who's injuries picked up injuries.
Anderson - 6 Permanently locked in the last chance saloon. Will go on display in the museum after he retires.
Nani - 7 Fantastic when he's not infuriatingly shit.
Tomasz Kuszczak - 7 Reserve keeper. Did well, then fell victim to the Ronaldo slave academy.
Carlos Tevez - 7 Fat, stupid, and surprisingly excellent for a free (ish) player.
2008
Manucho - 5 We have a habit of signing slightly useless reserve strikers for reasons no one can really explain.
Rafael - 8 Mop rampage
Fabio - 6 Injured mop rampage
Rodrigo Possebon - 5 Looked great until Pogatez ruined his career.
Dimitar Berbatov - 6 Didn't seem the type of player needed at the time. Also cost more money than any other United player. Ever.
2009
Zoran Tosic - 1 Signed only so we could sign another player who we then changed our minds and didn't sign.
Paul Pogba - 5 Could have been one of our best signings. Allowed to leave for free due to bout of monumental and prolonged feckwittery from club.
Ritchie De Laet - 5 Liked him. Not sure why it didn't work out at Norwich.
Antonio Valencia - 8 Bit of a genius signing. Brought in to be good at a specific thing so other players could benefit in Ronaldo's absence.
Michael Owen - 6 Spent most of his time at United talking about horses on the internet. Was free
Gabriel Obertan - 3 Michael Silvestre had sex with a peperami, and this is what happened.
Mame Diouf - 4 Didn't understand the point
2010
Bebe - 0 Someone who shouldn't have, made a lot of money out of this.
Chris Smalling - 7 Some kid playing as a semi-pro ends up looking the business for Manchester United. Fantastic
Javier Hernandez - 9 No one knew who he was. So good he scored against Manchester United for his old club AFTER Manchester United had signed him.
2011
Anders Lindegaard - 7 Another back up keeper signed to be a back up keeper and who then gets stick from fans for performing as a back up keeper.
Phil Jones - 100 Manchester United's greatest ever player.
Ashley Young - 6 When your main strength is running about a lot, this is both a good and a bad thing
David de Gea - 7 How high his rating ends up depends mostly on how long he sticks around before fecking off back to Spain.
2012
Nick Powell - n/a. Looks slightly like a Spitfire pilot.
Shinji Kagawa - 7 Fantastic at football. Misused a lot thus far.
Robin van Persie - 8 Volleys 'n shit.
Angelo Henriquez - n/a Angelo Hernandez
Alexander Buttner - 5 A semi-decent winger signed to pretend to be a fullback, while another actual fullback is sent on loan to a club where he doesn't play
Wilfried Zaha - n/a. Already scorned by some for wearing the wrong shirt to his medical.
There's a lot of 5 or lowers in there, but to be fair, they're nearly all reserve or low key signings that cost minimal amounts. Veron has to be the biggest flop. Not sure who I'd pick as best but there's a fair few candidates.