I recall using HelloFax to sign and fax legal/tax forms, an upgrade from having to do it physically. This takes it to a new level of convenience; now one may apparently sign/fax docs, clicking right through docs stored on Google's cloud, which is a pretty nice reduction in friction.

EDIT: I'd also add that when you have a busy day, having a simpler way to manage/deal with periphery tasks like faxing, makes a significant difference to your workflow. I don't have a need for faxing people right now, but bmarked for when I do.