When blogging, I didn't like the fact that all the feed readers were anonymous. At least with an email list one can see someone's email address and contact them no matter whether they've stopped subscribing or read your emails. Even with Friendfeed subscribers, one can discover quite a lot about a person, and then contact them directly in most cases with a little bit of investigation (like a LinkedIn profile, blog feed or YouTube account that one might explore.)

While the anonymoity and ease of subscribing to RSS gives it appeal to surfers, the former aspect can still be unattractive to writers, especially with lurkers and non-commenters often going above 95% of a blog's traffic, thus the lack of a feedback loop can make blogging unattractive, (poor return on energy, feelings of depletion to others - at least on HN there's mod-points, profiles and the likelihood of replies to encourage hefty postings) and also with advertising or sponsorship unsuitable unless a blog is extremely trafficked or focussed. The difficulty with blogging on FriendFeed is it only allows micro entries. Also, micro-entries can be too interspersed with one's other feeds.

Solution: startup offering key-based RSS urls individualized and presented on a blog site if readers are logged-in to the startup site (or hold a cookie). Also, by revealing a reader identity to an author, the author can at most tailor their writing and find offers or opportunities for readers, and at the least continue blogging. The idea is also useful for bands as they release new material to fans. There can be an option to prevent the display of non-keyed RSS URLs (ie you must be logged in to see the rss URL on a blog page.)

This idea would be useful for a new startup networking site, a tipping site (eg Tipjoy), comment site (ie Disqus), networking site (ie Linkedin, Younoodle, Friendfeed as a way to promote each one's service and make it useful offsite) or a web analytics site.

Alternatively, Google could reveal blog readers to blog authors with information from Reader, provided readers opt-in to the feature and setup a profile, and blog owners claim their blog.

Personally, I may restart blogging if such a service existed, likewise I would also be very happy to use it when subscribing to others. Right now I only blog mainly via linking to HN comments on my Friendfeed.

From experience, I know that anytime I contacted a blog reader whom I had known about, they were generally always helpful for whatever the reason, but many readers just won't contact the author, so it became a guessing game as to who was reading my material. Even in a blog posting if you ask readers to email you, they won't because it's tacit that there's no obligation. So rather than setup a list of 500+ LinkedIn contacts who I barely know, a typical blog (ie an exercise in charity to some extent), I'd rather keep a blog using this startup's feed-identifying tool, and then I can contact and network with those on my reader list if the need arose. This is something Calacanis can do to a greater extent with his list than he could've done with his blog (which incidentally I never was interested in): identify and contact readers who cannot lurk so easily.