Pali Keyboard for Windows XP and Vista
Table of Roman-script Pali encodings
For general use I recommend the excellent Times Extended Roman, available from the first link below. I use this as my default web browsing font instead of Times New Roman.
The Tibetan & Himalayan Digital Library -- Unicode Diacritic Fonts
Association for Insight Meditation
Buddhist India, by T.W. Rhys Davids (transcription in progress)