Wikipedia: Renaissance Music
Even though Wikipedia usually is not an accepted source for scholarly research, it can be a good place to start. In this case, students may use it for research.

Internet Public Library 2
Many safe, scholarly articles for students to use.

INFOhio's Biography Reference Bank
This is a good place to search for Tylman Susato and possibly other Renaissance composers.

Naxos
Classical music streaming

Digital Josquin: An Innovative Audio-Visual Experience of Renaissance Music
An informative 5-minute video

Renaissance music 1400–1600 (from the Victoria and Albert Museum)
A series of 6 articles with sound files

Audio files of Renaissance music
from Wikimedia Commons

Renaissance Instrument audio files and explanations
from Iowa State University

AllMusic.com