Probably the most obscure form in my repertoire is the local TriMet self-employment tax, due from sole proprietorships and partnerships. We've always filed as a partnership, using the federal tax ID for Dawn Wicca and Associates, which is what I'm doing for 2006 as well.
TriMet provides excellent transportation services in this area. I like seeing where my money is going. This is a tax I don't really mind paying. DWA (not publicly traded) owes $209 on its TMSE this year, revenue to Oregon's department for same.
I got my 1065, K-1s, 1040 and OR Form 40 filed last week (these pair with the 1099s and W2s on the other end). The whole process felt very stagecoachy and wild west. These schedules are every geek's nightmare of accumulated cruft. I hope the company town ecovillages get a better API to the feds, this time with more help from real computer scientists.