Since lots of people out there use Gmail, and it's "conversation" e-mail grouping is awesome, why not take advantage of this and use a consistent e-mail subject (this is what really matters when gmail tries to group messages, apart from sender) when sending notifications?
It would allow, for example, that the "modifications to a image" e-mails sent by Skitch become grouped (perhaps by image?).
Even for those who don't use Gmail, this makes easier to filter, for example.
Today some people that commented one of my images asked me how to stop receiving e-mails from skitch, notifying about new comments.
I told them that should be a link to unsubscribe on the e-mail received, but this isn't true. They just have a little text, with a link to the page.
This is a huge problem. They SHOULD be able to unsubscribe.