All of the commercial ebooks of Rapture of the Nerds are DRM-free, thanks to Tor’s policy of only selling books without DRM. You can buy these ebooks secure in the knowledge that you can convert them to any format you want, lend them, give them away, or will them to your heirs — just like the dead-tree editions.
USA:
Amazon Kindle (DRM-free)
Barnes and Noble Nook (DRM-free)
Google Books (DRM-free)
Kobo (DRM-free)
Apple iBooks (DRM-free)
Amazon
Booksense (will locate a store near you!)
Barnes and Noble
Powells
Booksamillion
UK:
Forbidden Planet
Waterstones
Amazon
Canada:
Amazon Kindle (DRM-free)
Kobo (DRM-free)