I finally got around to registering with "Share Your OPML" this weekend. I like the idea of being able to compare my subscriptions with others and thought it might be a cool way to learn about some new feeds. I didn't realize it before, but it turns out I currently have 354 feeds... which is nowhere near the list of "most prolific subscribers" (rick pogg -- 8,210 feeds?!?).
To me, the coolest feature on the site is the "Subscriptions Like Mine" option -- it essentially compares my subscriptions to the subscriptions of others on the site. The more shared feeds there are, the greater the "strength" number for ranking similarity... which is nice because I can see a highly-ranked user's feeds and pick up some additional subscriptions that are likely to be of interest. This feature and the "Who Subscribes To..." feature had me clicking around and exploring feeds for quite some time.
I did run into a couple of issues with the site, but nothing too worrisome. First, there are two options for providing your OPML subscriptions to the site -- upload an .OPML file to the site or provide the URL for a file elsewhere. I tried to go the URL route, but that didn't work -- just a blank page after submitting the URL. Not a big deal, though I do think pointing to an URL makes it easier to keep my list of subscriptions up to date.
The second thing I ran into was a blank page when trying to view the subscriptions for some of the top names on the "prolific subscribers" list. I'm sure it has to do with the volume of feeds, though I was able to get at pages for subscribers with over 3000 feeds (yikes!).
Some other features I'd like to see are a sense of activity (how many people use the site? how many total feeds?), timeliness (how often are new users joining the site? when was a user's feed list last updated?), and some UI niceties like sorting (based on feed/subscriber counts, etc). Based on the "Community Weblog" and developer-oriented mailing list, it's hard to tell how much new activity there is around the site.
Getting an OPML file for my subscriptions was pretty easy with FeedDemon. Simply choose the "Export Feeds" option under the File menu and select which feed folders to include. I then hand-edited the file to remove a few feeds that are personal/internal feeds and would just clutter up the public subscriptions.
In doing this, it occurred to me that a cool feature for FeedDemon would be to auto-export and upload an OPML file from time to time. I probably add/remove 5-10 feeds each week (and suspect that my total subscription list stays in the 350 range). If FeedDemon could be told to export an OPML with a certain name and upload it to a certain location on a daily/weekly/monthly basis, that'd work very well with the SYO site (assuming the "enter an URL" option were to work correctly). Many bloggers provide an OPML file for their subscriptions directly on their blog, so this would have value beyond just the people using SYO.
On the other hand, with NewsGator Online, maybe the ideal solution is for NGOS users to have a unique URL that would provide a dynamic OPML and per-feed options for being included/excluded from the public OPML. Looks like the NGOS "Locations" option may get me close... I'll have to research that some more soon.
In the meantime, give Share Your OPML a shot... you're likely to come up with a few new feeds for your aggregator.