I was over at Staples yesterday, picking up a new hard disk and some other goodies, when I walked by a bin full of 1G USB keys for $29 each. $29 for a 1G key is a good price, so I grabbed one.
For some time, Microsoft has been promoting a new technology in Windows Vista called ReadyBoost. ReadyBoost caches the pagefile, extending the virtual memory cache onto USB memory, if available, rather than using the hard disk. Since flash memory is 10x faster than disk, theoretically it should be a significant performance improvement.
Sounds cool! Moreover, using ReadyBoost is trivial. It's just an option that appears anytime you plug in a USB connected device.
So how well does it work in practice? The performance boost was immediate and obvious. Applications load faster, the hard disk pages less often, and the machine generally feels much more responsive. That 1G key now has a permanent home in one of the rear USB ports on my PC. It's the best $29 I've spent on performance in a long time!