Distributed Version Control "killer applications"

Considering switching to Mercurial or Git? We are too. I'm currently studying the benefits of DVCS which turn out to be vast, lust and must.

I would love to hear from the community typical usage patterns.

Let's create a "Top N" productivity feature list for DVCS (based on Mercurial, Git or alike).

Please describe work flows that prove to be productive for you / your team, procedures that DVCS helped you achieve/improve as well as blunt "good stuff" that DVCS gives you (don't assume stuff are clear to the novice user).

I think that such a list could help folks approaching the team with a DVCS suggestion.

This question is community wiki, obviously.