Gel recommendations?!?

I want to purchase a gel, any recommendations?!? And yes I tried searching here in the forums but it will take you atleast an hour to find the right thread. Thanks everyone.

For what type of light?

For Speedlites, just go get the Rosco Strobist kit, which has 4-5 sheets of each of the most common gels, plus a few that you might use a bit more 'creatively'.

For monolights or pack/head systems, most big photo stores will sell gels in larger sheets.