Frontier ville is a great--all inclusive, site that is (as of this post) frequently updated. Check them out for a head's up on all new challenges!
Frontierville Tips is a great site to visit if you're just starting out. Check out their QUESTS section to move you quickly up the ranks!
Frontierville Helper is another super site to visit that has everything you need all in one spot! It's also frequently updated (as of this post) and easy to use.