Free fonts are good, though I'm not so sure I'd want to use any of those as a body font. Title pages or headers, though, no problem.
SIL has some decent fonts available for free. Specifically, I like the
Charis and
Gentium packages. The nice thing about these is that the license fully allows for embedding and redistribution.
There's also the URW Fonts collection that you can get from the
Ghostscript page. It includes clones of several classic typefaces, including TNR, Helvetica, Optima, Garamond, Palatino, etc. That package is licensed under the
AFPL, though I'm not really sure how embedding/redistribution of those fonts is handled. At the very least, they're free to use for your own purposes.
EDIT: And after a little more digging around, I came across the
Font Squirrel site. These can all be downloaded for free, but redistribution/embedding will depend on the license for each one. ("Free for commercial use" does not necessarily mean that you can redistribute it.)