Well, I much prefer Georgia for reading. Trebuchet is nice but it only works on some sites in my opinion. Other than that, Helvetica is nice too (not really that good for the web, but, alas, I'm not an Arial hater either), though I still think Serif typefaces are better for long text. I am a bookworm though and most books are written with a Serif typeface, so it may also depend on what your eyes are used to.
I do agree, however, that Trebuchet is quite nice. It's just not a typeface I would choose often for body text.