At Pragmatic Marketing, we're big believers in ebooks. Ebooks establish your authority long before a sales team starts working the deal and will ease the way for the sales team dramatically.
Our ebooks on The Strategic Role of Product Management and Living in an Agile World are great tools to get things rolling internally. And definitely check out the ebooks from David Meerman Scott, the king of ebooks!
If you've been thinking that you want to write an ebook, I recommend The Ebook Ebook from Jonathan Kranz. Also check out his 10 Reasons Not to Hire Jonathan. What a kidder.