The mifflin st jeor equation was found by experimentation to produce the most consistently accurate BMR [1]. You can find it on wikipedia [2]. As for tracking calories, I use my own software for this, which is what I'll be releasing soon, but right now myfitnesspal.com is the de facto standard.

[1] http://www.ncbi.nlm.nih.gov/pubmed/15883556

[2] http://en.wikipedia.org/wiki/Basal_metabolic_rate