According to Reddit, last month they had more than here 71 million unique visitors. Yesterday, alone, there were 5,487 active subreddits. With all that activity, comes the need for more and better organization. That's why they're re-introducing multireddits that let you create your own public reddit front pages with a selections of subreddits.
From reddit:
"This functionality has been around for years in the form of creating custom URLs like/r/space+nasa+astronomy, but the goal is to make these distinct slices of reddit as ubiquitous and powerful as subreddits. In the process of curating and sharing these different front pages, there lies the potential to breathe life into smaller, more specific communities, because you can now participate in an order of magnitude more of them."
This feature is rolling out with community involvement and is currently only available to reddit gold users. Users are encouraged to create their own, custom reddit front page and test it out at /r/multibeta. If you're not a gold user, but want access, send reddit a postcard.