Homegrown Key Rotation
Most of the security packages that change out WEP (Wired Equivalent Privacy) encryption keys are corporate/enterprise oriented packages that involve lots of components, and often use 802.1X, a standard for logging in over wireless and wired LANs. WEP keys can be cracked in somewhere between 300 and 10,000 packets, depending on many factors and who you talk to.
Saferwep is a clever Java-based alternative for Macintoshes that rotates WEP keys to improve network security by reducing the chance of a brute-force crack. It's not optimal, but it's an interesting idea.