I'm sure many of you already know, but if you see an ad for an eBook on sale, and it's not for your reader, it's a good idea to check the store that's attached to your reader.  A lot of times, several stores have the same offer even if it's not advertised.  I received an e-mail for a $5.00 eBook sale at Borders.com, and I found that the books that I wanted were also $5.00 at Amazon.

Very true. I almost purchased a Kobo book until I realized that my Kindle would not read it!

And if you find a freebie special, odds are other sites will have the same freebie.  A lot of Kindle freebies you can find for free on B&N also so they're already in the right format for you.