“Bacn” – pronounced as “Bacon” – is spam (kind of), but not really the lewd, disgusting, “killing my inbox” type.

From Jargon Watch at Wired.com:

It’s not really spam. You want to read it (and probably would), you just don’t have the time. Thanks to the folks at PodCamp Pittsburgh, there’s a new web-term you can now use specifically for these types of e-mail notifications. Things like bill-payment receipts, Twitter requests, newsletters, project notifications—all are bacn.

Here’s more if you want more.