So you want a cool rep title....

what are your options? How hard are they to get? And which ones are in jeopardy with the coming of Cat?
Never fear, I'm here to answer all those questions.

First, Ambassador. Get exalted with all 5 home cities. This has gotten easier since the Tournament, but there's still a bit of leg work to do. If you're allergic to jousting, your options are questing and cloth turn-ins. There's probably going to be at least one faction (Gnomer for Alliance, and I think Thunder Bluff for Horde) where you have to do cloth because the quests aren't enough. Farm up some runecloth, you're going to need it. This one isn't hard, just time-consuming. On the plus side, you can get a ton of mounts, giving you a leg up on Mountain of Mounts.

Second, Bloodsail Admiral. You've got to get friendly with the Bloodsail and hated with Booty Bay. You get a nifty hat and a pet. This one's just grindy. Possibility of being affected by Cat: medium.

Third, Guardian of Cenarius. Garetia's currently working on this. You need to get Exalted with both the Cenarion Circle and the Cenarion Expedition. For Circle rep, there are some quests, as well as killing Twilight Cultists in silithus, doing world pvp (also in Silithus) and running both AQs. For Expedition, run Underbog and Slave Pens or turn in Unidentified Plant parts till honored, then quest and run Steamvaults. You can also grind ears in Borean Tundra and turn them into to Dehta. If you can't solo Steamvaults, or don't have someone to duo it with, this is really not fun. Steamvaults is 3k rep per run more or less, so beg, borrow, or steal someone to come with you if you need to.
You have some nice possibilities with this grind, including mounts out of the AQs and blues/greens from the instances. Possibility of being affected by Cat: fairly high.

Fourth, of the Ashen Verdict. Get exalted with the Ashen Verdict in ICC. Run ICC and/or do rep runs of the trash. You can get recipes, a really nice ring, and um, other stuff? Possibility of being affected by Cat: low insofar as Cat's unlikely to change the grind, but it's going to be much harder to find people to go with you.

Fifth, of the Shattered Sun. You must be exalted with the Shattered Sun offense and do a quest and it'll cost you. This one involves lots and lots of dailies on Quel'Danas. Possibility of being affected by Cat: low

Sixth, Argent Champion. Get exalted with the Argent Dawn and the Argent Crusade. Run Strat (or Scholo, but Strat has a mount drop) with the Argent Dawn trinket and/or kill old world undead for Dawn, and wear a tabard/quest/do dailies for the Crusade. My priest can solo Strat in disc (it's slow but completely doable) so this is likely the most accessible of the titles involving old world rep. Possibility of being affected by Cat: medium. I'd get exalted with Dawn before Cat, just in case though.

Seventh, the Diplomat. Go from neutral to exalted with Timbermaw Hold, Sporeggar and the Kurenai / Mag'har. Now this one is a big grind. You can combine some of the Sporeggar rep grind with the Cenarion Expedition one (Underbog is full of Sanguine Hibiscus and you can get them from bog lords in Steamvaults too if you're an herbalist) Sporeggar has a pet and the Kurenai/ Mag'har have awesome land mounts. This is a really grindy one, and be aware that you want to get to Revered with Timbermaw through killing alone, saving your rep turn-ins for Revered to Exalted. Timbermaw's a great way to farm runecloth, so you can get some work done on Ambassador while you're at it. Possibility of being affected by Cat: fairly high, so get Timbermaw done now. Again, you'll be doing at least one of these grinds for mountain of mounts, so might as well go for the title.

Eighth, the Exalted. Raise 40 reputations to Exalted. So, if you've done all the ones above, you're at...15 exalted reputations. Expect to spend a long time working on this one. Possibility of being affected by Cat: Almost guaranteed. Get working on those old world rep grinds now.

Ninth, and last, the Insane. So called because you have to be insane to have gotten it. Earn Exalted status with Booty Bay, Everlook, Gadgetzan, Ratchet, Darkmoon Faire, Ravenholdt, Shen'dralar, and Honored with Bloodsail Buccaneers.
Massively grindy, expensive, and if you're doing this, I'm impressed. Worried for your sanity, but impressed. Possibility of being affected by Cat: pretty much guaranteed, given that these are all old world rep grinds.