1. Sapphire Warps. Specifically the "Bubble" warp. Holy mother is it useful. The default makes it look like ass (see also: many other Sapphire defaults) and a reasonably useless random distort. But if you dial the octaves up, then mess with the frequency and aplitude you get controllable and scalable fractal edges. It's great for making gmask shapes organic and noising up edges at high frequencies. At low frequencies, it's great for general distorts.
All around, just fantastic for getting some organic nature into your comps.
2. Matte Curves. This really should be on my top five for December, but this is the first post, and Matte Curves are totally sweet. They're basically a glorified "blend" logic op. The curves affect the gamma in your foreground and background mattes. Whenever your key's edges are just a little too dark or light tweak this before you start wading through edge erodes, flashes and blurs. I've had it save some nearly impossible keys.
3. Batch Paint. Much like the modular keyer and batch and all the "nodey" stuff, people are generally scared of Batch Paint. I know I didn't use it for years. That's a shame, because it's awesome. While it doesn't have all the features of desktop paint (autopaint, some of the wash modes) it's so much better. You can add layers, clone from layers, repo layers, scale them. Then you can swap your inputs and all the effects are still applied. Works great in proxy mode to boot. Never have to re-paint something because a grade changed again. Always always always start with batch paint now.
4. Color Warper. I used to be about 50/50 on the CC/CW front in my setups. Lately I've been going more to the warper. Most of my work involves some look creation, and it's so much faster to whip around the trackballs, pull secondaries and bend gamma curves in the CW. The CC's still a great node, but for trying out different color looks, the CW is number one. (or four)
5. Sapphire Textures. Substance Noise is a nice addition, but it's still rather clunky in it's interface (loading different textures as opposed to a drop down menu), and few of the textures animate in any useful way--most just break up into layers. Sapphire, the old standby, again, has awful defaults, but once the octaves are dialed up and the frequency adjusted, Textures really shines. The basic "Folded" is my favorite and the one I use 80% of the time, but the others can come in handy from time to time as well.