I scan negatives in with Vuescan as 2400 DPI JPEGs, and then put the results into Aperture, archiving the original scanned files in case Aperture decides to die on me at some point. The actual post-processing tends to be one or more of:
1. nothing at all - scan, import, leave alone;
2. mess a bit with the white point and/or curve in Vuescan - but not often because it's easier to mess with pictures in Aperture;
3. in Aperture...
3a. boost shadows. This is the most common thing I do - most of the pictures I take seem to need this to some degree.
3b. remove dust, scratches, fingerprints etc
3c. auto white balance and auto levels for colour negative film (I can never get the colours right in Vuescan). For similar reasons I will sometimes play with the saturation and colour balances generally if I feel the result isn't what I saw.
3d. rotate if I've messed up while taking the picture, which happens a lot with folders and TLRs;
3e. anything else that I feel like doing for fleeting artistic reasons, such as cropping and colourising.
One of the reasons I don't shoot in colour negative much (apart from that I can't develop it myself) is that I find it very hard to scan. I almost never seem to get good results without heavy messing-about, which takes time and is rarely that rewarding. Slide film on the other hand always comes out lovely. If I were stuck with just Velvia and HP5+ I'd be perfectly happy.
eta: oh, and one of the most important things I do in Aperture is tag pictures and adjust other metadata like star rating, date, time and location. I have a Bento database with all of the rolls I've taken by number, listing the camera, date developed, development time etc, and I tag the images with "roll180" or whatever so that I can find them again. That's the most useful part of Aperture for me actually - as long as I've spent the time, I can find, say, all the photos I've taken of tables in August 2010 rated four or more stars. Not really post-processing perhaps.