There's nothing in particular that I do for yearly maint. because I'm always fiddling around and adjusting or maintaining equipment throughout the entire year.
On average, I'd say check the typically most neglected systems: hubs and headset. If it's been a harsh winter, you're likely to at least need a hub repacking.
__________________
"I feel like my world was classier before I found cyclocross."
- Mandi M.