@John: Nice plugin. I had a couple thoughts on this. First one is a link to the edit profile page right next to the progress bar. I was also thinking of using a lightbox. That would slide out from the side of the page when a users logs in. Reminding them to finish their profile.
@ClubUgly: Unfortunately, if you are using profile nagger with the 'default widgets' plug-in, the widgets you set as defaults only show up for users who have created their accounts after you have made those changes. This is a flaw in the 'default widgets' plug-in, not my Profile Nagger. One work-around would be to alter the user details php file to include my nagger code in it.
Also, I have a newer version of this plugin here Profile Nagger , so download that one if you haven't already.