A few of the books listed in Boswell's Bibliography can be found on the Internet:

Free E-texts

The Journal of a Tour to the Hebrides with Samuel Johnson, LL.D.
(from Project Gutenberg)

Life of Johnson
(Abridged and edited - from Project Gutenberg)

Non-free E-texts

Questia, The Internet's Largest Library is an inexpensive subscription-based online library, offering more than 400.000 books and journal articles online. Some Boswell-related books and articles are in there as well, including the Boswell: The Ominous Years 1774-1776 volume of the Yale trade editions, and a 1924 Oxford University Press edition of a (large) collection of Boswells letters from 1778 until 1795, the last letter being the depressing one where Thomas David Boswell informed William Temple of the death of his old friend.