All in Flash:

Guitar fretboard trainer
http://www.musictheory.net/trainers/html/id81_en.html

Keyboard trainer
http://www.musictheory.net/trainers/html/id80_en.html

Note trainer
http://www.musictheory.net/trainers/html/id82_en.html

Key trainer
http://www.musictheory.net/trainers/html/id83_en.html

Interval ear trainer
http://www.musictheory.net/trainers/html/id90_en.html

Scale trainer
http://www.musictheory.net/trainers/html/id91_en.html

Chord ear trainer
http://www.musictheory.net/trainers/html/id92_en.html