What can i buy as a present for a girl?

How old is she?

Wow, it really depends on the girl. There's a huge amount of options. Jewlery usually works Something to wear could be nice too, but could also be a disaster. You can always go for the less adventureous options of a book or a CD.

The best present I ever got was a two-day horseback riding trip. 

Like Sohpie said, it really depends on the girl, and also on the nature of your relationship with her.  Most girls like to be surprised (I think), so first of all, don't go for taking her to pick something - always buy something (worse case make sure she can go replace it). Second important thing is buying something for HER - meaning - think of what she likes, what she'll enjoy, and not what you might enjoy like a sexy lingerie item which you think is really sexy, but she would actually find totally uncomfortable...

 Try and think of things she might have mentioned she really wanted to have, or maybe things she could find useful or be interested in that she didnt actually think but would be happy to get...

 If you share her taste in fashion, jewlery, bags...I would go for one of those. If not - taking a sister, mother or one of her friends with you that know her taste better - can also work :)

 Good luck!

I disagree. If you surprise her by taking her to a shop and saying "which one do you like?" that's ok.

The question is also how much you want to spend. If you have lots of money, well, diamonds are a girl's best friend. If this is someone you pal around with, you might go for something a little less costly, like a stuffed toy animal.

If the girl lives with her parents, then gifts for the house are kinda no fun, unless it's something special for her room. If a girl lives on her own, then house gifts might be nice. If she likes to cook, try to catch her ogling kitchen gadgets. I'm dying for one of those fancy mixers (Kenwood or KitchenAid).

An MP3 player or digital camera might be nice, if she's the type for it and doesn't have one. Again, it's a matter of budget and of who the girl is...

And if it's me, I'd like a car please...