It's called Autopatcher and it basically allows you to download all Windows Updates, hotfixes and patches to an external USB device. You then can take this and plug it into any Windows-based PC and run the application from the key. It will check and see which hotfixes and apps you're machine needs to get it up to date. I use it everytime I build/re-build a PC. It sure beats downloading all these patches everytime!
There are a bunch of other 'extras' in this was well; common registry tweaks and nifty utilities. Best of all, this is FREE. Check this cool little app out!
**Update: Looks like Microsoft has contacted this team and has threatened legal action unless they stop. Well it looks like there is a glimmer of hope that this project will continue in some alternative fashion... check the Autopatcher.com site for updates.