Just once piece of advice after reading through this thread: Wait until you're completely over the person before you decide whether to keep or throw away. You're less likely to run into regrets that way.
My story is similar to Spoilsport's. I used to keep everything, especially from my first serious relationship. The problem there was that the relationship was an act of desperation on my part -- thus my own clinginess, "romance," etc. Looking back now, I think virtually everything I did was ridiculous, so I have no problem with getting rid of mementos.
Actually, I take it a step further and sell some of the gifts she gave me on ebay and amazon

Just sold a book today!
I'm evil, sorry.