There's no way to give gifts as far as I'm aware either, and like Pallyndrome, it was a very neat aspect from the Sims 2 that I think should be added to 3. While I might be wrong, I seem to remember that the ability to give gifts was also made available in Sims 1 by one of the later expansions...although there weren't many options on what to give.
Edit: If you really feel compelled to have your sims give paintings/photographs as gifts to their friends, you could just go over to their house and try to hang the paintings on the wall!