Being that this is the week of the Faire it seemed more than fitting that we cover this reputation grind. Darkmoon Faire is another reputation that players will encounter fairly early on in the game but unlike any other it is a mobile one. In addition to that this rep is one I would classify as an "Oh shoot me now" in the grinding department. While with the advent of Inscription it has gotten EASIER that by no means translates into EASY or CHEAP.
The first Friday of each month a barker will show up in Ironforge and Orgrimmar announcing in which of three possible locations the faire will be located: Elwynn Forest, Mulgore or Terokkar Forest. (At Level 6 he will also have a quest for you sending you to the faire.) There you will see it being set up by the Carnies but you can not really be able to interact with it until the following Monday. Once the Faire is in full swing there are a variety of level limited turn in quests you can do for Tickets which can then be turned in for a variety of prizes. This is ONE way to gain rep with them.
Besides the repeatable quests there are also the famous Darkmoon Faire cards. Now Wrath and the introduction of inscription changed some things with these. Before the only way you could get cards was as drops in either the Old World or Outland. Now certain decks can be crafted by inscriptionists. In addition to this the trinket producing decks no longer become soul bound when turned from a deck into a trinket. (Patch 3.1.1) So anyone who gathers these decks can turn them in for the rep then put the TRINKET up on the AH.
Now...since we all know I am Cheap...(I mean thrifty) what is the most cost effective way to gain exalted with these guys? There are two thoughts on this, either farm Vibrant Plumes or if you are an inscriptionist to make 1680 rogues decks. (The advantage of the Rogues decks is they can be turned in at anytime not just when the Faire is in town.) Personally for the inscriptionists out there (or maybe even for those others with some cash to burn) my personal suggestion would be to pick up the lvl 80 decks when they are CHEAP turn them in for the trinkets then sell the TRINKETS when the faire is not in town as the DECKS give you the most rep of ANY other quest. This is NOT a rep grind for the faint hearted that is for certain only the TRULY dedicated go after this one...or the Insane.