Ricci Adams' Music Theory.net: This is a theory class favorite! It is wonderful for beginning theory drills and ear training exercises. You can also track your own progress throughout practice time. http://www.musictheory.net/
Teoria: I love this website for its variety ear training exercises, and some get fairly advanced. You can certainly learn something new about theory with its large collection of articles and tutorials. http://www.teoria.com/
Sonic Fit: Another great site for both written and aural skill practice or lessons.http://www.sonicfit.com/
Sight Reading Factory: Here is a way to practice sight-reading at home and prepare for our sight-reading assessments. You can customize the example and amp up the difficulty as your skills improve! https://www.sightreadingfactory.com/
Practice Sight-Reading: Another customizable way to practice your sight-reading technical skills. http://www.practicesightreading.com/