http://turnpaige.com/2008/04/01/ophelia-by-lisa-klein/
Just stumbled across this mini-review of a young adult novel that appears to be a retelling of Hamlet, from Ophelia's point of view. Not really my cup of tea, but I thought I'd put it out there in case it looks interesting to folks. I don't know if the reviewer keeps calling Ophelia Hamlet's wife because she's simply mistaken about the plot, or if the author of the book has gone ahead and taken that liberty.
The questions at the end, by the way, are complete spoilers. Just in case you're thinking about getting it. Then again, who knows, the spoiled bits might make it look intriguing enough to get anyway.
Back in college, in my playwrighting days, I started a project of a similar nature. I did a Rosencrantz and Guildenstern Are Dead take on Hamlet, where the whole play is done from Ophelia's perspective. The gimmick being that when she's "offstage" she's speaking in modern English, but as a character from the play comes on stage she falls back into character to deliver her lines. I did not muck with the story - my reverence for the text dates back at least that far :) - but I did make the leap that Ophelia was in on Hamlet's feigned madness and just playing along...until she realizes that he has actually gone mad, or at least, she can't tell the difference.
Never finished it.