You create subscriptions to RSS files, and when you request to view new items, the subscribed RSS files are downloaded, and you can then view each individual new item.
The idea of weak subscriptions is that you do not want to read each item from each subscription. Rather you want to see which links occur in the largest number of different web pages that you have weak subscriptions to. The subscription is "weak" in the sense that you have some interest in the content of a blog or other regularly updated web page, but not so much that you want to scan each individual new item on the page.
It makes more sense to create a weak subscription to a web page, because these will contain actual links to items of interest. RSS files for blogs tend to contain mostly links to the blog owned by the owner of the RSS file.
To make the most of weak subscriptions you will probably need to create quite a few of them: everytime you read a personal blog where you share the authors view about what is important or interesting to at least some degree, create a weak subscription to that page. You will want to weakly subscribe to the front page of the web log that is regularly updated, not to an archived page.
Use the "bookmarklet" provided on the main menu to create weak subscriptions quickly and easily. However note that these bookmarklets don't work reliably on the latest version of Internet Explorer. They do work OK on Mozilla. Other browsers have not been tested. Any help to fix the problems mentioned would be gratefully received. The final solution to this problem might be some sort of browser toolbar.
After making some weak subscriptions, you then want to "harvest". This involves all the pages being downloaded (subject to headers implying that there is new content), and recording all the linked absolute URL's recorded on each weakly subscribed page. Then go to the Mentioned URL's page to see which URL's (that you have not yet "visited") are mentioned by the greatest number of weak subscriptions. Within a given number of mentions, mentioned URL's are ordered in descending order of last mention date, which is in effect the same thing as the date in which that URL acquired its current number of mentions. Note that multiple mentions of a URL in one weak subscription only count once.
In many cases the URL's that have the most mentions are themselves web logs, so you can use the page of mentioned URL's as a good way to find more web logs to create weak subscriptions.