Refer to the above quoted threads by all means, but in a nutshell, just look for BEER ALCHEMY.
Reasonably priced, very editable/customizable and very Mac.
Written from the ground up by a Mac user for Mac users.
I don't rely on software too much to tell me what I should be doing (my tastebuds do that better than the software can) but the software can be useful for sharing recipes, scaling them, and doing rough calculations.