Ask HN: Will this browser cookie method work?

I'm in the process of building a social media website that basically recommends new websites to users based on a number of categories they have selected (similar to stumbleupon). I want it to be useful to users even if they are not logged in. I've devised a method, using cookies, to keep track of content that a user has already been recommended, which is important. I realize I may be going about this all wrong, so any feedback or suggestions would be appreciated!

- I have DB that includes a table for each category (images, videos, funny, politics, etc) and each row in these category tables contains information about a particular website.

- When a user goes to my site they select the categories they want to explore (which is saved to a cookie) and then they can add a bookmarklet to their browser which when clicked will take them to a recommended site from one of those categories.

-When the bookmarklet is first pressed, a database call is made that grabs the 100 most recent link_ids from each of the users selected categories which are then loaded into a new browser cookie. (so if they have three categories selected it will create three new cookies which each contain a comma delimited list of 100 link_ids for that category).

- If the bookmarklet is pressed again it will detect that the user already has category cookies, it will pick a random category, grab the link_id list, pick a random link_id from that list (probably have to turn it into an array first), and then overwrite the cookie with a link_id list that is identical to the previous list except that it doesn't have the chosen link_id in it. This way, the next time a link is loaded from that category cookie it won't load the same link. It seems like this would prevent a user from seeing the same content over again (as long as they don't delete their cookies), which is basically what I'm trying to solve. Even if a user does delete their cookie, chances are that a decent period of time has elapsed since they last visited the website, and thus the 100 most recent links grabbed from each category will probably be new to them anyway so their won't be much reoccurring content.

I know it's kind of strange, but does anyone see any problems with this method or a better way. Just wanted to get some feedback before I proceed because it's going to take some time to implement.

Thanks!