Vanitygen is a command-line vanity bitcoin address generator.
If you're tired of the random, cryptic addresses generated by regular bitcoin clients, you can use vanitygen to create a more personalized address. Add unique flair when you tell people to send bitcoins to 1stDownqyMHHqnDPRSfiZ5GXJ8Gk9dbjL. Alternatively, vanitygen can be used to generate random addresses offline.
Vanitygen accepts as input a pattern, or list of patterns to search for, and produces a list of addresses and private keys. Vanitygen's search is probabilistic, and the amount of time required to find a given pattern depends on how complex the pattern is, the speed of your computer, and whether you get lucky.
The example below illustrates a session of vanitygen. It is typical, and took about 10 sec to finish, using my Core 2 Duo E6600 CPU on x86-64 Linux:
$ ./vanitygen 1Boat Difficulty: 4476342 Pattern: 1Boat Address: 1BoatSLRHtKNngkdXEeobR76b53LETtpyT Privkey: 5J4XJRyLVgzbXEgh8VNi4qovLzxRftzMd8a18KkdXv4EqAwX3tS
Vanitygen includes components to perform address searching on your CPU (vanitygen) and your OpenCL-compatible GPU (oclvanitygen). Both can be built from source, and both are included in the Windows binary package. Also included is oclvanityminer, the vanity address mining client. Oclvanityminer can be used to automatically claim bounties on sites such as ThePiachu's vanity pool.
Current version: 0.20
Get the source from GitHub. Includes Makefiles for Linux and Mac OS X.
Main discussion at BitCoinTalk