RE: Blue light or Blue Blood Tracker?
I have used (unsuccessfully) Starlight Bloodhound. The stuff comes in a bottle similar in size to a jug of Windex. It should come in a 55 gallon drum, because that's how much you'll need.
I carry one of those rectangle-shaped disposable flashlights that firefighters use. You can pick em up for 2.29 at WalMart (light, bright, durable). I also bought an LED head light made by Energizer - the best $13 investment I've made in a while. (runs on three AAA batteries for about 60 hours)
For more involved tracking jobs (gutshots, etc.) A rechargeable spotlight works great, but I'd wait till morning. Nothing illuminates quite like mother nature.