Not sure if this is more what you are after, but check out Scrivener 2 (http://www.literatureandlatte.com/scrivener.php) or YoJimbo (http://www.barebones.com/products/yojimbo/). Maybe thats more what you had in mind? Oh, and check out Curio as well. http://www.zengobi.com/products/curio/
ABC = Always Be Compiling.
I use my iPhone's voice memo, before that I carried a simple Olympus digital voice recorder (it's about $50 for one that'll hold about 10 hours).
At home, I use Yojimbo and Shovebox. Yojimbo when I'm actually writing, Shovebox when I quickly need to paste in a one-liner, or throw a link to something that inspired me.
When I'm preparing new material, I take all these various snippets and start picking out what works with my mood, the crowd (based on area, people I know who frequent the place, how long it's been since I've performed there, etc), and the like. And I put them together in a separate Yojimbo note.
Then, I perform for my webcam and time myself. I'll record 3-4 different attempts at the same bit and then see what I can change, what needs finagling, certain wording that sounds good, etc. Also, I figure out how lengthy each bit is, on average.
Before I leave the apartment, I put together a set based on the aforementioned criteria, taking into account how much overall time I'll have onstage that night and how well the material will go together. I write down each bit's working title on its own line (i.e. "Irony & A Dick Punch") and I try to perform the whole act to myself while I'm driving to the gig.