My tuner has been working on a pretty sweet datalog analysis program, I find it a lot easier (and faster!) to use than Excel or Ecutek's built in datalog viewer. It's also a fair bit more powerful than Datazap.
It makes things like visualizing fuel trims a breeze.
Check it out here
http://blog.vittuned.com/viperdata/
Software is free and the user guide is on the same page as the download link.