http://www.chromium.org/getting-involved/download-chromiumChromium builds do not auto-update, and do not have symbols. This makes them most useful for checking whether a claimed fix actually works.
This is the raw build of Chromium, right off the trunk. It may be tremendously buggy.
Consider Chrome Canary or Dev Channel for a build that regularly auto-updates to latest.
Chromium for Windows x86: https://download-chromium.appspot.com/?platform=Win
Chromium for Mac: https://download-chromium.appspot.com/?platform=Mac
Chromium for Linux x86: https://download-chromium.appspot.com/?platform=Linux
Chromium for Linux x64: https://download-chromium.appspot.com/?platform=Linux_x64
Chromium for Android: https://download-chromium.appspot.com/?platform=Android
Related: Looking for Chromium OS?