This search string alone gives you lots of places to look for them. There's also the store at milehighcomics.com, if you need another resource for covers. Also, there's google, haha.
But seriously. This might be interesting. I'm presuming there are still some people who read comics here.
Fun thread is fun! Great picks so far. I'm gonna go with these since I haven't seen them here yet. But yeah, JH Williams pwned 2009 with his Batwoman covers ^_^
Daughter is sick - I was tired - didn't even see the 2009 in the title. Here's my three then - I'm sorry for making a goof - Technically - not a comic book - but this was intriguing ...
Well most of my favourite covers are already up here (Invincible Iron Man #21, Northlanders #17, Scalped #30), but a couple more took my eye last tear...
2000AD #1633 - This cover and the story "Cradlegrave", actually made me start reading 2000AD again after many years.
Captain Britain & MI-13 #12 - This was a variant cover to mark the 35th Anniversary of Wolverine. I just really like this style, so different to what you usually get from covers.
Deadpool - Merc with a mouth #3 - Need i say anymore?
I'm going to have to echo the praise for the Batwoman Detective Comics covers and also the Unwritten covers. But in the interests of diversity...
I've loved this adaptation so far, and the range of cover art has been a highlight.
Simple and powerful.
And as and honourable mention, I'd say the three-part cover over X-Men Legacy 220/221/222. Can't find a pic online of the three stitched together but they look great layed out next to each other.