If you podcast or run an independent radio show, the PreSonus Firepod FireWire interface with preamps is a must have. It has an 8 mic capability, so more than enough for your co-hosts and guests.
This thing is solid. We use one in one of our control rooms in the 2 million dollar studio I work out of, and I have one for my broadcast studio at home. Some people get a mixing board, but you really don’t need it these days unless you record giant projects, or you’re just trying to impress. You can run a mixer out of your audio software.
It’s not the newest tool but it is, in my opinion, the best, and has withstood time.