InsaneTek

Here are 7 easy steps to safely test Chromium OS on your netbook using a 3GB+ USB flash drive:

1. Download the pre-built .img file from here.
2. Download Image Writer for Windows here.
3. Open Image Writer and select the chromiumos.img file you downloaded and the drive letter of your USB drive.
4. Click "Write".
5. Remove the USB drive from your computer.
6. Plug the USB drive into your netbook.
7. Turn the netbook on and log in to Chromium with the username facepunch and password facepunch.

Thanks to Hexxeh for building this image file. You can find instructions for OSX and Linux as well as an FAQ on his website.

You can find a Chromium OS hardware compatibility list here.

Note: You may need to use a wired network connection because many wireless cards are not supported currently. There is a modified version with wifi drivers available for Dell Mini 10v users but it has some quirks and the download is super slow (<20kb/s for a 7.5GB file).