The homepage for all Stack Exchange sites is intentionally simple: it's a list of the last (n) questions by activity date.
Activity date means new questions, or questions with new answers or new edits.
This has worked reasonably well for the last two years, but it is breaking down on Stack Overflow due to the sheer volume of questions per day. Right now we get about 2,000 questions per day -- more than one new question per minute.
Roughly a year ago I doubled the default number of questions on the homepage from 48 to 96. This was no longer sufficient. Now we attempt to display a thirty minute span on the homepage -- up to a maximum of 192 questions. At peak times this is not enough, either.
In the face of massive incoming question volume, the Stack Overflow homepage needs to change:
If you are an avid user, we don't expect you to use the homepage. You should be browsing by tag or tag combinations that interest you. However, users don't seem to discover browsing by tag very easily, even though we have literally hundreds of tag links on the home page. We need a better way to drive users off the generic all-you-can-eat-on-any-topic homepage towards their tags of interest.
We need a way to aggregate questions by tag on the homepage, without sacrificing the core "every question gets featured on the homepage for a little while" mechanic.
The homepage should still be, fundamentally, a list of questions that reflect what the site is about. New users who stumble upon the site for the first time should see "ah, so this is what this website is all about". It should be obvious.
How would you propose redesigning the Stack Overflow homepage to meet these needs? Please provide mockup screenshots if possible.
(Any change would, of course, be specific to the Stack Overflow homepage only; none of the other network homepages would change. Stack Overflow the only site that has anything even close to this volume of questions.)