Simply: Some Multiblock structures that needs to be build around the Conveyor belt.
Belt will deliver items in, it will take a few sevonds, end-product comes out.

What could be there for example?

Furnace: Can cook a whole stack at once, need a 3x3x4 (h_w_l) structure. belt goes into the center of h*w

Crusher: Turns blocks into their Dust-Form (or other things that can be crushed - cobble to sand for example) 3x3x5

Sawmill: Turn Logs into Planks, Planks into Sawdust. 3x3x4

Slaughter: Send animals or mobs in, get a product out. 3x4x4

if you have not enough energy to power them, or the item you send in can not be used, it will send out the item you send in.

Already planed but in a more world based plan. The items will pass under or threw the block to be processed. They will not actually go into the blocks but remain on the belts the entire time. I plan to create a belt based version of most of the common ore processing machines.

For the furnace i'm going to keep it one block two two block tall. However, the more furnaces a person lines up in a row the faster the items will be processes by the belt.

Crusher i have a few models laying around that i worked on 5 months back. When Calclavia and Briman were still part of the project they rejected the ideal of belt machines. Instead they wanted me to just work with other mods leading to Mekanism getting to were it is cough. Really wish i had force there hand so we would have very effect machines for assembly line.

Slaughter machines i don't even want to think of doing just for the fact of what it is. However, these type of machines are so easy to create in minecraft already. I use 4-5 different methods for my mob grinders using things from fire, armbots to lasers.

i'll add to this more later...

yay :)