I found a good bag (notch above ziplock bag for $0.50) that could work as a first aid bag, when looking around for headsweat gear. So far, all first aid stuff recommended by the gang could fit into this bag. Okay, everything but the defibrillator, but my 220 volt power chord is too short to make the defibrillator practical.

The Do Wrap company also makes a slightly smaller bag, that comes in silver, which would be easier to see in the dark.

6.5" x 4.5"
http://www.dowrap.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=DWMWC&Category_Code=WP