It is not possible - and not the purpose of this site - to cover all aspects of "Music".
Nevertheless, at this page a number of Music Resources are listed.
Many of these are very interesting to keyboard players - and other musicians as well.
Jim Bottorff - Banjo songs etc.
Bob Keller's Jazz Page - Resources
Computer Music - Make Music Now
Freebies - Free Books on music
Software Sequencers Online Advisor
Video: Figure Out Chords To Songs
The Ultimate Beginner’s Guide To Recording Drums
abc notation - text-based notation
Takt - Text-based Music Programming
Yamaha Press Room - Piano/Keyb.