Music Sequencing Software for Unix?

caluml asks: "I am looking at getting more into music making, and buying some decent-ish synthesizers. Most sequencing software out there is for Mac or Windows, neither of which I have. I have looked at Audigy and Audacity, but wonder if there are any others that others find worthwile. Can anyone give me their recommendations for sequencers, audio editors, and multi-track recording software?"