Potassium...not too much to say about it really, but I feel it deserves some credit.
Recovery Ability - I was experiencing 3-4 calf cramps per week, with some of these being multiple calf cramps. These always happened at night, and nothing really seemed to help them. I decided to purchase some potassium at Wal-Mart in hopes of it doing something. I've been taking it [99mg] the past few weeks every night before bed, and I've not had a single cramp during that time. Consequently, I no longer wake up with sore calves in the morning.
Value - These pills I purchased only cost $3-4.00 at the local Wal-Mart. I no longer have terribly rude awakenings accompanied by some fairly unpleasant pain.
This is honestly one of the few supplements that I can say was worth every penny, and it doesn't even cost many pennies at all. If you suffer from night time cramps, check into taking this prebed.