Regardless of what you call them, the small portable memory that anyone can afford can be used for many things. As an introduction to the possibilities, I would like to direct Masonic Technology readers to the article 10 cool things you can do with a USB flash drive by Greg Shultz over at TechRepublic.
In his article, Mr. Shultz touches upon usages ranging from using the drive as an MP3 player, to locking your computer.
Overall, the article does an outstanding job of introducing the versatility of portable drives, but do not limit yourself only to the article. A quick search on google will provide many other sites and articles that may just have the thing you were looking for all along. I, personally, did a search using only the terms portable apps and found an outstanding resource on makeuseof.com entitled 100 Portable Apps for your USB Stick (Mac and Win).