IMHO, anything which changes the raws in one way or another is cheating, whether that be a stone => wood reaction, making steel free, or making dwarfs move super fast. However, there are degrees to cheating; stone to wood, especially if it converts three or four stone to one log, is not completely reprehensible, as is modding soil to sand. Using smelter reactions to make adamantine free, or to produce diamonds, emeralds and rubies by the truckload, is somewhat uncivilized. Personally, I primarily use cheats for those things that I need quickly and which aren't too bad, like bags for all the seeds I have everywhere, red stone for color-coded levers, or the material I need to satisfy this last mood/mandate.
Actually, since you asked for a big list, here are all the cheats I use:
[SOIL_SAND] is the tag which states that a given type of soil is sand suitable for glassmaking; add it to any soil you have to make it into glass.
[METAL_ORE:100:{METAL_NAME}] is the tag which makes a given mineral an ore, like hematite has [METAL_ORE:100:IRON]. Add it to any rock you like to turn it into any metal you like, even alloys.
[REACTION_CLASS:FLUX] does just what it says, and is primarily useful for steel production. Again, any rock you like.
In general, to make smelter reactions free, remove the lines with [REAGENT:...] and the [FUEL] tag, to make the product require nothing at all.
[PRODUCT:100:10:ROUGH:NO_SUBTYPE:STONE:{VALUABLE_GEM}] can be added to any reaction you like to make that reaction output precious stones as well.
[PRODUCT:100:1:WOOD:NO_SUBTYPE:WOOD:OAK] can be added to any reaction to make it output wood.
[ITEMCORPSE] uses the same syntax as reactions, more or less, but should not be used because it replaces the original corpse with the item.
Adding [SPEED:1] or [SPEED:0] to the dwarven creature entry makes them move super fast, but does bad bad things to FPS at higher populations. I use it strictly for setup, building walls, dumping stone, and digging out large tunnels for plumbing.
Most injuries can be healed via nose amputation; save and quit, then open the dwarven creature entry and remove some single tag from the BODY tag, I use the nose. Open and load your game, save and quit immediately, and replace whatever tag you removed.
[trADE_CAPACITY] tags appear on wagons and some pack animals; set them to some insanely high number to get insanely large quantities of stuff. Bear in mind, though, that large loads mean long unload time.
Meta-cheat: You can add more than one [METAL_ORE] or [PRODUCT] tag to a given mineral or reaction, to make more than one product at the smelter. Or, you can change the chance from 100 down to 20-50, to reduce the cheatiness.