virtual talmud

Mishna at wikisource.org - much more complete than the Talmud section (see below), but still does not yet feature the Mishna in its entirety. Has introduction original Hebrew text, translation, and further explanation/commentary. Great resource. Can also print out a page or two at a time for a long commute!

Talmud at wikisource.org - incomplete. also has a Hebrew language site. Only Nedarim and Berakhot currently have content.

E-Daf - Daily page of Talmud. Can listen to shuirim in English, Hebrew, or Yiddish. Scanned image of each page. Also includes 'Daf Digest' two-page newsletter about each day's reading.

Mechon-Mamre - Complete list of Mishna, only in Hebrew. Formatted nicely for printing.