How portable is portable? And how much are you looking to spend?
There are some Gitzo legs that are very light (being made of Carbon fiber), but they cost on the order of $600 just for the legs.
Anything made by Bogen Manfrotto is very nice, and there are some very nice support systems that can be had for about $300, granted that they aren't going to be as light as the Gitzo.
Most everything else that you look at will be crap- some will vouch for the longevity of their Silk and Velbon tripods, but from what I've experienced, they tend to break 6 months after you get them.
You can also spring for a tabletop tripod, which will certainly be more portable, but perhaps not quite as useful.