MixMeister BPM Analyzer
Full user review
Simple to use, free, the only BPM analyzer I found with any kind of accuracy.
Be aware of 1/2 beats and double beats.
Cross-checked results produced by this with other sources and found to be amazingly accurate.
Just be aware 1/2 beats in songs may double the BPM result and double beats may halve it.
No other programs came close.