sonicbirth

here's a program that i've used in the past to create vst and au plugins. made some synths in it but mostly just effects plugins. it's called sonicbirth. freeware for mac. it's a pretty awsome program if you're not great at command-line programming but still want to make some awsome effects really quickly. it's kinda similar to Max in that you have objects that you drag and drop and connect by lines. it differes in that each "circuit" can be zoomed in on so that you can edit smaller details and build subcircuits and the like. doesn't have half the power of max though and it's a bit trickier to interface with midi.

along the left side is an editor for all the parameters of a specific selected unit. on the right hand side is a list of components to choose from. on the bottom is an audio server thingy. it lets you play sound and tells you how much cpu is in use.

up top is a closeup of a plugin i made that allows you to select a crossover frequency and then treats each output with a bit-depth reducer and a sample-rate reducer. it's pretty cool when you use it in ableton to affect a drum loop.