Probably my favourite "obscure" race (it's not really that obscure, it's in the MMI, I just hardly ever see them in use) is the Aranea.
Lupins (Dragon Compendium) are cool. They're LA+0 Monstrous Humanoids and have Ride as a class skill for all classes
One of my very favorite feats is Fell Conspiracy in Exemplars of Evil. Great party-wide benefits for very reasonable costs.
Feat: Hardened Criminal from City of Stormreach (how's that for obscure). Gain Skill Mastery in a single skill, and immunity to intimidate to boot.
An obscure item I really like is the Rod of Ropes (Complete Scoundrel). Costs 4000 gold, and you can use it as an extendable rope up to 300ft, a rope with a grappling hook that you can use to hook onto things or people, or a rope with a sliding tool on it.
Spell: Shark bolt. Imagine scorching ray, except instead of flame rays, it's sharks. How cool is that.
Item: Amber amulet of vermin. These things are wildly underpriced for their effect. Only 700 gp to drop a massive scorpion on your enemies' heads? A bargain.
Prestige class: Urban savant. Easy to get into