These are great. Simple, quick, cheap, reliable, fast, and to the point. I had a couple 2GB HP flash drives that I just replaced with 8GB HP flash drives now that the cost has come down quite a bit. I like them because they are streamlined to be easily carried around on your keychain. If you always have your keychain in your pocket, like most people, then you will always have storage space on hand. I have two on my keychain. One is for PortableApps (google: PortableApps), which is a very cool way of being able to run your own applications (Firefox, OpenOffice, Media Players, IM's, etc) on other people's computers without having to install anything on their computer. It is completely "take everything with you". The other one is to boot into a live Linux that runs off the USB drive without touching a HDD. Especially useful when you need to use various utilities to fix someone's computer: such as HDD partitioners, boot loader managers, ability to mount an NTFS drive and replace a corrupted file that is preventing their Windows from loading, text editing, etc, etc.
Like others have mentioned, the cap does not fit on the drive very tight so it will only be a matter of time before it gets lost. Others have commented about using string (glue or drill a hole) to keep the cap from getting lost. I didn't even bother. I just took the caps off and threw them into a drawer somewhere. I just carry the drives on my keychain without the caps. They won't get damaged.
These USB flash drives also have a built-in LED that illuminates during data transfer, so you can be sure that there is no data being transferred before disconnecting them. This will prevent possible file corruption.
It would be nice if HP made these drives in different colors other than black, so you could color code them for your various uses.
These, obviously, aren't secure (encrypted) USB flash drives, so if you are looking for something that you plan on using with sensitive information (and the possibility of it getting into the wrong hands), look elsewhere.