We use a product named "Scannerz" for disk and system troubleshooting. It can find disk surface problems and help isolate bad cables, etc. Personally I think it's a bit for the more technically oriented, but I guess a fair number of people are using it.

A word about USB thumb drives with OSes installed on them. TAKE THEM OUT OR WHEN NOT IN USE DISABLE SPOTLIGHT INDEXING ON THEM. I made that mistake with one that was 32G. I put Snow Leopard on it as an emergency boot flash drive, and because there was so much space left over I started using it to transfer files on it. One day I went to write to my trusty thumb drive and it was rendered read-only. I found out that Spotlight was continually updating the indices on it, and it depleted the write cycles on it. Remember an thumb drive is not an SSD - it's not intended to handle continual reading and writing.

As an FYI, I think it was installed in the USB slot for about a month continually (more or less) fot that to occur.