Personalized RSS Feeds
Brad Feld wrote an an interesting piece damning personalized RSS feeds, but I disagree with several of his points.
I think his concern is partially valid, but only partially. Take the case of a personalized feed of my.earthlink.net (basically an RSS feed of a personalized home page). Any aggregator can implement a heuristic to the affect that if there is only one subscriber to a feed, the aggregator does lazy polling on the feed -- that is, the aggregator only polls when the user logs in or starts a new session, and then only keeps polling while the user maintains a session.
If 10,000 my.earthlink.net RSS subscribers all have their personalized URL in Bloglines, Bloglines uses their lazy loading heuristic. If people start to share their personalized feeds, Bloglines determines a lazy loading v. prefetch tipping point (say 10 subscribers to a given unique feed).
In terms of the security concern: here's my personalized My EarthLink feed. It has my local weather, some stock tickers I follow, my horoscope, and some other random stuff. Fairly boring to anyone but me. Not enough personally identifying information to do much damage, and no way to back out from that URL to a username and password for the actual personalized portal site.
As for his point about messing with tracking -- I totally agree. Providers shouldn't use a unique feed ID to assist in tracking unique subscribers. There are much better ways for that.