It is nice not to have to download any programs if you want to record simple screencasts and demos (and in SIMPLE steps) of your computer screen.
Here is an good review of ScreenToaster by Jane Hart.
What is even better is not to have to create yet a new username and password for yet another website. That is where ScreenJelly differs from ScreenToarter: although ScreenJelly works pretty much in the same way, you can simply login with your Twitter account… Well, if you don’t have a Twitter account yet, go get one and play with it at least to know what the hype is about…
ScreenCastle is another simple, one-button, Java-based screen recorder that works with not need for complicated software installation. It is based on Skoffer, which offer a useful option for the bloggers out there: if you are an advanced (well, somewhat advanced) user, you can use their API to build plug it into your existing website for even quicker recordings.
Best of all, these tools are free of charge (as of this writing).