so, what do you buy adults in your life that don't really "need" anything? I always have this issue with my parents especially. So my dad gets a motorcycle/aircraft themed tee shirt or possibly books while my mom gets gift cards and candles/lotion, etc. They aren't normally much help either, as they always say "aw, nothing" when you ask what they want.
So i did find a tee shirt for my dad. While i was thinking about what my mom would want, i came across Oxfam Unwrapped. I've donated to Oxfam before and participated in some of their petitions and letter writing campaigns. They've got gifts from $18 which gives blankets, mosquito nets or water jugs to those in need to $10,000 which builds a house on stilts. Very cool. Check out the goat.
Another site is Changing the Present. It is amazing, with gifts from tons of organizations and prices starting at just a dollar! That gets a child a day's worth of anti-retrovirus meds! have 5? you can give a 80 lb bag of concrete for a playground or two books to a child. Gotta spend $500? That pays the transport costs for hospital equipment in Africa. Pretty cool. You can search by price, by cause or by the gift recipient (like for Dads, Moms, Weddings).
I know Oxfam has a pretty good rating for charities. As Changing the Present is basically an aggregator of lots of charities, you may want to pull up a search site like Charity Navigator to see about the individual organizations if you feel iffy about a place.
Happy giving! I'm actually excited about my mom getting the card saying she's given school uniforms for kids overseas.