In my previous Advanced Dungeon Crawl Classics (ADCC) post, I looked at a simple method for adding warrior subclasses to the rules. This led to some discussion on G+ of doing the same for the other classes. There’s some obvious room with the demihumans to do so, though it should probably be limited so humans remain unique in their variety. Personally, I feel that wizards are already strongly distinguished by patrons (and potentially the Arcane Affinity spell). Clerics are obviously distinguished by alignment (which I previously expanded upon), but I can imagine a scenario where clerics could be further distinguished by deity or type of service.
Thieves are also distinguished by alignment in the rules as written, though I believe it makes more sense to allow a thief to simply choose a path at 1st level. This effectively creates three thief subclasses in the rules and also provides a straightforward manner for adding more — new paths. Along those lines, I present a first crack at a new thief skill set, the Path of the Bard.