In the car, I use a Plantronics M155. $26 on Amazon.
http://www.amazon.com/Plantronics-M1...nics+bluetooth
Solid headset. Supports A2DP as well. I've used it at my desk quite often to just listen to music from my phone or whatever.
EDIT: I also wanted to note that it connects to my phone FAST. You flip the switch and it connects within a second. This is very handy for me. I keep it in a small clip on my dash powered off. Normally I'll listen to my phone's music over my head unit via bluetooth. If I get a phone call, the head unit wants to answer, but I don't like the sound quality that it picks up when I talk. If I get a phone call that I need to answer I'm able to slip the M155 out of it's holster, flip the switch on and, by the time I stick it in my ear, it's connected to the phone and I can press the button on it to answer the call. When I'm done, I switch it off, put it back in the dash holder, and music picks back up on my head unit. Pretty spiffy.
For working out, I finally went with a pair of JayBird Freedom 4's.
http://www.amazon.com/Jaybird-Freedo...bird+freedom+4
As noted by Chrono, it does sound awesome and fits in the ear really well, but is twice as much as the more common LG set I see in the gym. There's one reason I avoided the LG. The neckband. I did not want a neckband resting on me when I was trying to run or lift weights or something. I was also unconvinced that it would stay in my ear during activity. If that's not a deal breaker for you, then I would recommend the LG set over the JayBirds simply on price alone.