If you're rocking a PC with limited RAM, a flash drive can help speed things up if you're running Windows Vista, 7, or 8. Simply slap that puppy in and choose to speed up your PC's performance with ReadyBoost when prompted.
(If the option doesn't appear, right-click on the flash drive in File Explorer, select Properties, and open the ReadyBoost tab.)
ReadyBoost uses your flash drive's memory as a cache, to speed up access times for your hard drive. Flash drives aren't as fast as traditional RAM, and you won't even be allowed to use ReadyBoost if your PC has a decent amount of free memory, but the tool can definitely help on older PCs with 1GB (or less!) of RAM.