Guess I need to write comedy, next book. Never knew I was that funny. =)
On distribution:
Right now, most industry estimates have Amazon holding about 70-75% of consumer ebook sales. B&N holds a share somewhere in the teens - together, these two represent roughly 90% of all consumer ebooks sold in the USA. The remainder is mostly taken up by Apple, Kobo, and Sony (not necc. in that order, but Apple seems to have the #3 slot sewn up solidly at this point). Smashwords, Google, Diesel, Webscriptions, and buckets of other smaller companies plus authors selling on their websites fill the remaining couple of percent of consumer ebooks.
So off the bat, if you place a book on Amazon, B&N, and Smashwords (Apple, Kobo, Sony, Diesel) you have distributed to at least a high 90s percent of the overall US market. Additionally, you've distributed to the major players in most of Europe, Australia, and Japan (Apple/Amazon, with Kobo as a rising star investing heavily in those markets).
OK, that would sew up a statement of "almost anywhere". I mean, if you're in 98% of the market, and the e-publisher is in 99%, you're pretty much in good shape.
But I said "anywhere". And I stand by that. If you have a digital book market someplace that's accessible to e-publishers that you think a self publisher can't get into, tell me, and I'll demonstrate that it's possible myself.
In digital publishing, distribution is a very even playing field.
Edit: The question, I feel, remains not "what can the epublisher do that I can't?", but "is that epublisher offering me a good balance of services they render for percent of my income they are taking?" The answer to that will vary from writer to writer, and needs to be figured out individually by each of us.