I use a Niterider Pro 700 Race in front with one or more Niterider Lightningbug 3s on my helmet if I'm on my heavy commuter, OR I have the two bugs on my bars and the 700 light on my helmet for the road bike. Seems almost anything bigger than those blinkies will jam the cyclocomputer on my roadie.

When it's helmet mounted, I nicknamed it the "Eye of Sauron". Brings cars to a quick halt who were just about to roll through a stop. I love the Niterider. Beautiful color temp, beautiful even light pattern, excellent battery life, and built like a freakin tank!

Then I've got either two superflashes (one on me and one on the bike) or a superflash and a Cateye TL-LD560-R. I always like to have two in the back just because I've had batteries quit suddenly leaving me invisible from the rear - a bad situation!