Got a personal best today. My regular climb 2.7 mile ~6% climb to the top of Twin Peaks in San Francisco. I hit all the lights (three of them) and made it in 00:18:20. It wasn't even all that hard; the trick for me was pacing myself so that I could push myself harder on the (relative) flats.
I've also been finding that sitting and spinning (in the saddle) helps build stronger muscles for the flats; standing builds more the muscles for... well, standing.