Nike + and similar running equipment

[Supergoal]

I bought the Nike plus chip (that slots into the trainer) a couple of months ago since I thought it would be great for motivation and keep a steady record of my running, but I just feel a slight nag that it isn't doing things as accurately as I hoped for.

Does anyone else use this and is there any better or good software available to use with it for the iphone/ipod. Perhaps something that also tracks my running path using GPS.

[FatGit_UK]

I use my Nike+ chip on the default settings and it seems reasonably accurate enough for me. I use it more for an indication of my progress/development than for measuring the actual distances I've run, but comparing it to mapping websites such as mapmyrun.com it's normally fairly close for runs up to about 8 miles or so. The two half marathons I've run recently it's come up a bit short at about 12.6 miles, but I've never got around to trying to calibrate it, so not sure how much difference that would make.

[charlesr]

I've got a polar GPS. It's great, but pricey.