The Legal Information Institute (LII) at Cornell Law School and the Center for Computer-Assisted Legal Instruction (CALI) have created electronic versions of the Federal Rules of Civil Procedure, Criminal Procedure, and Evidence. The ebooks work on iPads, iPhones, Nooks, or any device or software that supports .epub files (Kindle support is coming soon).
The ebooks are available to download for free, but the LII does accept donations to fund these types of projects.