You name it!
Wanna make peppermills, make a 1 and 1/16 peg to drive it, that way you are not using an "inside grip" which will loosen, if a tool catches.
Wanna make face pieces for desk mags? Make a corian flat surface, rounded to the proper diameter (just under 3 inches), glue that to a piece of scrap poplar 2 x 2, use two sided tape.
Wanna make Bottlestoppers? Take a 2 x 2 poplar piece, turn to correct outside diameter for bottlestopper (just over an inch), then turn the end to 5/16" and mount your blanks on the 5/16 peg.
Lots of others, my ceiling (between rafters in basement) has about 20 nails with jigs on them.
Remember these are waste poplar. I make them and throw them away when they break, make a new one (sometimes up to TEN minutes). Amazing the things you can think of, if you allow yourself.
Whaddaya wanna make??