Are you familiar with Ambrosia Software? If not, let me tell you that they make some very competent tools. Two that from the looks of them could be very good for podcasting. I actually use one of them of a regular basis.
Snapz Pro X
Snapz Pro X is for a lot of people the go-to application on Mac when you need to capture what happens on the screen. I use it regularly to make tutorial videos and it’s incredibly easy to use. I definitely recommend it if you need to record what’s happening on the screen. Don’t take my word for it, try out the demo.
I have never used WireTap Studio, but my impressions about it after reading on the website as well as watching a couple of videos is that it looks really basic with few possibilities. However, what it does can be exactly what many podcasters need. It seems like it’s capable of recording any audio (i.e., besides from inputs, also audio from applications) which could be very useful to some. Another good thing is that it supports AU plug-ins.
Did I mentioned that they’re cheap?