The folks at TechSmith make a nice screencasting tool called Jing that I've been using for quick tutorials and various documentation. It comes in two flavors, free and pro, but interestingly, I've found the free versions limitations to almost be features.
For example, it only records 5 minutes of video. Personally I find that tutorials longer than 5 minutes to be too long anyway. If you're rambling on for longer than 5 minutes, your listeners are gonna move on.
Which brings me to another limit/feature... you can't edit the video. I also like this because I want to make quick tutorials... not monkey around with video editing. This forces the issue.
The free version only records video to swf (pro version does mp4) which again, is kinda nice. You can drop the resulting swf onto any modern browser (with flash installed) and the video will play. No additional apps required. It's also a *snap to embed in a web page (see below). Additionally, it runs on Mac & Windows, has nice stingers and can also do screengrabs with markup.
Now, that said, if you're looking to build a slick, more professional screencast, Jing will fall short. It's strengths are agility and functionality... pretty is another apps job.
*Update... okay, so there are some issues playing back swf files on windows :) Here's a link to the video.