1. Marketing guys
2. HR guys
3. The guys who invent the words like "synergy"
4. Anyone who works for RIAA or MPAA
5. cops who spend all of their time running speed traps. They're great the rest of the time.
6. salesmen who want to negotiate a price. Everyone should pay the same price for any product regardless of how good your negotiation skills are.
7. extremists of any type (environmental, religious, political, etc.). not really a profession, but still annoying.
8. guys who set up kiosks in the mall and try to sell you their worthless crap every time you walk by.
9. frivilous lawsuit lawyers
10. Technical recruiters who don't speak English well enough to be doing a telephone job.