Dog Questions

I am intrested in furthering my dogs training. They have mastered basic obedience and now I would like to take them further. I am not quit sure what I want to to teach them to do but they love learning(and so do I) so much that it would be a shame not to teach them all I can. I am not sure the names of the different types of training or what they include. Any and all info appricated. Thanks!