I haven't put much time into this, but off the top of my head I think these would be some balanced values which would not be overpowered:
1) Craft assistant - 1x1, +25% to manual crafting speed of the character.
2) Artificial organ - 1x1, +100 to health (+40% of base health).
3) Portable logistic computer - 1x1, +1 character logistic slots.
4) Additional tool belt - 2x2, adds 5 extra slots to your quickbar.
The changes I suggest are without changing their size, and ignores their cost to research or build. I would suggest making equipment like this larger (and scaled accordingly) for two reasons:
A: It's easier to manage equipment with fewer, larger modules.
B: You can tweak their shapes to make them fun to play with, and in some situations a given shape might just be a good fit into the remaining space on your equipment grid, improving its usefulness above just its raw attributes.
