Presents aren't people. Do you really *need* the useless present to remember the person you love? I'm willing to bet that they'd rather you reclaimed the space than kept a useless thing about the place.
I'm trying to (very slowly...) declutter and to buy fewer things. Bike kit is my big weakness. (And clothes; I manage that one by staying out of clothes shops & by reminding myself that I have *no more space* for clothes.) Not having very much spare cash atm helps.
Freecycle, Ebay, charity shops are all good. If you feel the consumerist urge, try those for acquiring new, as well.
If you haven't read/worn/used it in the last year, consider whether you really need it. If it's your best ball-dress that you only get to wear once every few years (yes, I do actually have one of these, thank you
) or a drill that you haven't needed because you haven't put any shelves up of late: by all means keep it. If it's a T-shirt, it can probably go. If it's a book: will you *really* reread it? Would you rather re-read it than go down the library & get another one? If not: pass it on to someone else. Then they get to read it.
Libraries & friends are great for books. I agree that there's no such thing as too many books, *but* I also know that a fair amount of what I have on my shelves is either shit or I won't re-read it. I don't want to buy or build more bookcases, so for me, there's a limit there. (Same with CDs/DVDs, which are Pete's weakness.)
My current method is 7-things-a-week: on Sundays, I spend 15 min finding 7 things (or thereabouts) to get rid of. It's slow, but it feels less overwhelming than a generalised "must get rid of stuff" aim.
The key is not to bring more stuff in...