I have just released a new version of the Nike+ GPX Chrome Plugin (Version 1.1) to fix a problem with only some accounts (thanks Aleix for pointing out the issue). It turns out that I needed to strip out the white-space in users screen names in order to request the list of runs. This is a small change, but let me know if stops anyone from working. I also formatted the distance and duration fields in the table to make it more readable.
I am still working on heart-rate monitor export support (sorry for the delay).