Is there a list of Unity 3's undocumented features?

For instance, I just discovered WWW.responseHeaders, which is very useful but not in the current documentation. Any other handy features that are easily missed?

If you find a feature missing from the documentation, you should file a documentation bug. WWW.responseHeaders is listed in what's new for Unity 3, but indeed it's not in the docs, so it's an oversight that should be corrected (as opposed to private APIs, which are inaccessible as of Unity 3 and intentionally not documented).