Update 1: See additional options in the comment section.
An overview of The Aeneid in English is here.
Online translations are mostly by Dryden. They come in various versions:
- The Perseus Digital Library
this also has the original Latin
- Ancient/Classical History at About.com
ditto with Latin
- Google Book
- Internet Classics Archive
- Project Gutenberg
Project Gutenberg with all the options
A Project Gutenberg version can most likely be downloaded for free on the iPad also.
Other online translations: