Note: I cannot personally vouch for the quality of all the materials offered on the external sites listed here. Some are more useful than others. Use your own best judgment.
To report errors or to recommend sites to add to this list, please contact me.
» The Pali Tipitaka Project (Vipassana Research Institute, India) contains the Chattha Sangayana (Sixth Council, 1954-1956) edition of the Tipitaka, transcribed from the Myanmar print edition.
» The Sri Lanka Tripitaka Project (in association with the Journal of Buddhist Ethics) offers a free public-domain edition (ASCII text files, zipped) of the Sri Lanka Buddha Jayanti Tripitaka edition of the Tipitaka and Commentaries (in romanized Pali). Although this edition hasn't yet been thoroughly proofread, it's still a tremendously valuable resource.
» BUDSIR — Buddhist Scriptures Information Retrieval (Mahidol University, Thailand) is a CD-ROM containing the Thai edition of the Pali Tipitaka and Atthakatha (commentaries) in romanized script. Cost: about US$300.
» Chattha Sangayana (Sixth Council) Tipitaka CD (Vipassana Research Institute, India) is a CD-ROM containing the Chattha Sangayana (Sixth Council, 1954-1956) edition of the Tipitaka, transcribed from the Myanmar print edition. It also includes the Tipitaka, Atthakatha (commentaries), and Tika and AnuTika (sub-commentaries), all displayed in seven scripts, including Roman and Devanagari. Cost: varies according to shipping destination.
» All Things Pali Discussion Group, a Yahoo! group, has some very knowledgeable and helpful members who can help you with your Pali studies. A most valuable resource.
» Pali Language Sources and Resources (Maximilian Sendor) offers an on-line Pali dictionary, an on-line edition of Narada's Elementary Pali Course, Pali sound files, and more.