I have discussed how to maximize your video for iPod Touch. Here are some tools that I use.
To grab videos from the Internet, I use Video Download Helper. It works with YouTube and pretty much every popular online video service. (does not work with Hulu though) It has conversion functions but I don't use it because it looks too complicated and there is a registration process.
To rip video files off DVD's, I use a free software called Handbrake.
I use Total Video Converter. Grab a stand-alone copy here. No installation, just launch the .exe file. It's simple enough for those with no video c0nversion background to understand. It can also convert across video and audio formats. But for some reason files converted to mp3 using this software is not recognizable by iTunes and thus the iPod.
For that, I use a Free Conversion Software.
Another tool I use is Clipnabber. It rips videos off YouTube and other video sites too. It has an auto-convert to MP4 download. Another good web-based converter is Media-Convert. Though it has an 80% success rate and doesn't support ID3 tag editing, still pretty useful for smaller files. I don't recommend using this if you're converting whole movies especially if you have a less-than-desirable Internet connection.