This will be periodically updated, to help prevent the tickets growing to unwieldy numbers of suggestions and possibly obscuring other tickets.

-Print a list of blocks needed for the machine to build it. (#5)
-Alteration/config for customized inventory sizes. (#7)
-Ecology Mod integration. (#16)
-Biome/temp/humidity restrictions for machines functioning (like desalination plants on beach/ocean). (#17)
-Vent particles for machine operation. (#18)
-Auto-building via creative mode. (#21)
-Expand mod-added crafting components from ingots to plates, gears, rods, etc. (#25)
-Additional machine adapters. (#39)
-Recipe Research limitations. (#42)
-Splitting fluid outputs/indicate insufficient fluid output tank space. (#47)
-Fluid Per Tick recipe control. (#48 #68)
-Ability to determine position of block relative to controller to aid in troubleshooting for pack builders. (#49)
-Mark blocks as functional for inputs/hatches/etc. (#55)
-Inventories within machine that are not explicitly input/output. Like storing fluids provided via bucket or filling buckets as the recipe. (#56)
-Modify tool durability/degrade item durability in recipes. (#61)
-Gamestages integration. Despite there being no good way to handle it. (#62)
-Custom blueprint textures/selectable blueprint textures. (#66)
-Specify output hatches to use for certain outputs, as when multiple fluid outputs are possible per recipe in order to prevent machine "gum up". (#67)
-Blueprint ordering within NEI/JEI. (#71)
-Prevent people removing items that aren't used up once recipe starts operating, "car key analogy". (#74)
-Recipe inheritance for machine tiering. (#77)
-Tool or "catalyst" input support. (#86)
-Connected texture support for blocks. (#90)
-Energy per tick recipe control. (#92)
-Customization of sounds on recipe completion/operation. (#96)
-Ability to modify cosmetic appearance of controller block based on machine tier/type. (#101)
-Ability to define a block for multiple functions (combination input/output, etc). (#121)
-Locking recipes in a machine, to not automatically downgrade if one ingredient runs out and the remaining ingredients also match a recipe. (#123)
-Multiple modifier block support. (#97 #117 #124)
-Option to hide blueprint slot if machine JSON does not require it once built. (#126)
-Supporting rotational changes of controller block. (#128)