The Prime Pages
- http://primes.utm.edu/
- Prof. Chris Caldwell's database of virtually every large or otherwise interesting prime number known; includes the 5,000 largest known prime numbers and records for specific types.
distributed.net
- http://www.distributed.net/
- A distributed computing project currently trying to take the RSA challenge of RC5-64, and also working on OGR-24 and 25 (Optimal Golomb Rulers). Previous projects included CSC and DES.