Pomegranate molasses: It adds real muscle to glazes. It's a double-barreled blast of sweet and tart flavors. While it has some Middle East connections, you can find it in most well-stocked supermarkets.
Chipotles: These are jalapeños that look as though they've done some serious time. They look old and wrinkled, and the canned version in adobo sauce looks as though it's constantly soused. Dried chipotle packs a little more heat and a little less smoke than its Spanish cousin, pimentón, and can shake up any rub.
Dried chiles: Technically, chipotles and pimentón are part of this crowd, but their smoking sets them at a distance from the other chiles. Dried chiles like ancho, New Mexican, cayenne, and bird (Thai) can run the Scoville scale. They should be ground with a dedicated spice grinder. Avoid pre-ground, nondescriptive chile powder. It doesn't pack the heat.
Tamarind: Milder than lemon and sweeter than vinegar, this souring agent likes to go undercover in marinades and tropical glazes.
Asian spice blends: Five-spice powder, Togarashi, curry, or garam masala. Asian spices tend to run in packs. Any of these spice gangs can have five or more members. Spicy with these groups does not necessarily mean hot.
Rice wine vinegar: Rice wine vinegar is like white wine vinegar on probation. It behaves itself, and is not that aggressive when mixing it up with sake, soy or mirin. It's probably the softest of all vinegars available.