ProClip makes one specifically for the AT&T Captivate. You start on their home page and select a clip for your car model and then the phone. I don't have one yet but they look OEM and their are several models to choose from. Guy on androidforums.com can get you 10% off, which you'll need as they...
I assume you mean recalibrating the battery as per this thread.
As for my phone use, I'd been working on increasing battery life all week, thanks to great forums like this. I use DCSwitch+ to turn 3G off until I want to use it (which is rare because I have WiFi at the office and at home). It's...
I did this Friday, was done by 1:45, and 49 hours later it was at 4%. Prior to this I had to charge every night. Used the Navi for an hour, downloaded stuff, and other light use--nothing really heavy like video, etc.