bitcoins.gripe (Can be used as forum & reviews for Bitcoin Investments)
Estimated Value: $3,670 (USD)
Why this is valuable
Comparable domains sold: bitcoins.de $21,420 (USD)
bitcoins.pw $299 (USD)
bitcoins.im $1,510 (USD)
Another extension sold with high price: bitcoins.de with a different extension sold for over $21420.
Short: bitcoins is 15 characters or less.
Extensions taken: The .com and 30 other extensions of bitcoins are in use.