I've used almost a dozen different programs but wound up sticking to grip. http://nostatic.org/grip/
It does automatic lookups if you want, puts files right where you want them, and also makes it easy to configure bitrate, etc, for encoding.

A general one is xcdroast, a GUI for burning CD's. It has some good ripping / encoding capabilities too.
www.xcdroast.org/

Both programs are free and I've seen them run well on Slackware, Gentoo and FreeBSD. Installation is pretty much automatic too.