Program for setting USE flags in Gentoo.
I've recently found a small app named ufed which helps you choose USE flags for Gentoo. It reads the /etc/make.conf and gives you a list of all the USE flags available and alows you to read a description, select and save new USE flags. It's usful since I don't know each and every USE flag off by heart.
If you want to use it:
emerge ufed && ufed