Version Tree
Created originally on Bitbucket by mweisshaupt (Martin Weißhaupt)
I had to work a lot with ClearCase recently and there is one feature, that I miss in Mercurial. Clearcase has a version tree which can be checked to see who changed a file and when did it happen on which branch.
Here is the help from IBM about the version tree concept.
And this is an example tree found on Google
I think this would be a nice addition to TortoiseHg.