Glad to see I'm not the only one into uncommon supports (and even happier to see people not refer to the meta or them being outside the meta). Personally, my top 2 uncommong supports are :
Poppy : Start with a coin and E>Q>W, max R>E>Q>W. Your goal in lane is to get level 2 early and have the enemy carry be next to a wall. At that point ,if he goes for the cs, you can probably 80-0 him with your adc. Build path is early boots into Trinity Force. Use your ulti to either turn ganks around or tower dive the enemies for easy kills (make sure to leave the last hit(s) to your adc so you don't eat those 3 tower shots when your ult wears off).
Veigar : Start with Ancient coin and Q>E>Q>W max Q>E>W. Get those Q stacks from the tanks (it may trouble your ADCs if you miss the tanks with Rank 1 Q, which is why I level it again at 3) and melee minions. Use that AoE stun to cancel the enemy's aggression (and get a little 50% hp poke in), and basically outnumber them. It's not unusual to see Veigar come out of lane with 1k worth of APs stacked up on Q. Build path is Targon rush into sightstone rush into damage.
I've also seen Bening Sentinel (eroticles on twitch) play a bit of Cassiopeia. You basically start with Spellthief's Edge taking Q>E>W then maxing E>Q>W. Evolve to Frostfang ASAP and get that early tear or chalice. Use your Q to triple-proc spellthief and deal some quite awesome damage. Your tool for laning is E. If you have a chance at all-ining, there isn't a slightest chance that anyone outdps you.
Lately I've also started trying support Shaco. Every single all-in lanes you will see will be a breeze, and winning against a poke lane is really hard. I've seen a few start with Spellthief's Edge and go AP, but it seems that I personally can't understand how to play him AP, so I go for a more traditional AD build (often it's Tiamat into Shiv, but I may try the Trinity-BotRK line). You always start with the coin imo, since like Shen, he can't proc spellthief well (JitB doesn't proc). I've only seen people start W, since it allows for wonderful cheeses and gank protection, but an argument could be made for E. Then it's E>W>Q, to get the maximum amount of poke, and the longer fear duration. In most cases the ranks in your deceive won't matter. Playstyle is straight forward... gain brush crontrol by pnating JitBs, and poke with E; if they try to engage, blow your whole kit on their ADC. Level 6+, use your ultimate whenever you have the mana for it if you're wining lane, it can be used to damage the ADC when he's pushed to tower (or zoning him entirely) or tank tower aggro and deal more damage to tower. If you're in a tougher spot, use ulti mainly to juke stuff (Cait's ult can probably be juked 100% of the time on 1200 ping).
The first two I've had great success even in plat (I used both of them in my promos), BS is using Cass in D1 and winning more than he loses (it takes a strong independant ADC though), Shaco... I'm still not convinced, but as a counter-pick to Leona or Blitzcrank, I would probably take him even in plat.
AD: 
Crit: 
Tank: 
