I put up the wrong link for e-tuners - here's the right one:
Basically, e-tuning is any tuner tuning your car remotely (i.e. without them being there with your car). So, this requires that you reflash a base map that they send you, you data log with the AccessPORT, send those logs to the tuner, they look them over and then make tweaks to your map, you reflash that new revised map, and the process repeats. If you go with an e-tuner, make sure you establish up front how many revisions they are willing to do until finished and whether or not they will do futher tweaks down the road if something comes up (and at what cost, if any).