favorite part of nike+ experience

I've had the nike+ipod setup for six weeks now, and I'm just beginning to realize the possibilities of the marriage between the iPod sensor and the online tool:

• Run Diagnostics: For each run I've logged, I get to see how my pace changes over the course of the run (slower as it gets longer, of course). On my quick 2-mile loops, I can see my progress at getting faster running up the steep hill that comes at the 0.6 mile marker. I'll reduce that "V" to a minor divot by the end of February if it kills me!
• "Compare to Best": An off-shoot of the diagnostics bit, this allows me to plot my fastest run against the current run to see where/when I ran faster/slower so I can work on consistently improving my pace.
  
• Challenges: I've set up my first challenge on the web site (40 miles in 4 weeks) and it'll track how far ahead/behind I am in reaching that goal as a stark reminder to get out and put in my miles.
  

Still a mystery to me: In the diagnostics, I'd expect my fartleks to be more pronounced on the pace curve. Either I'm really not going any faster than I think I am, or the length of the dash is too small compared to the overall run. I'll spend time this coming month figuring that thing out.

Oh, and one annoyance I've experienced so far: my Nano completely drained while I was out of the country on travel, so my first run back was logged out-of-sequence (as happening January 4, 2000) instead of December 16 as it should have. Gotta remember to sync the nano to my mac next time it drains completely so I can reset the date.