better content discovery

The main tag cloud shows most popular tags. Once the tag database gains maturity this cloud will mostly remain the same over the years. What is more interesting for users is what is happening now. Which tags are gaining most views and replies in the last X days? A tag cloud made trending tags...

It would be very useful to have the new posts sidebar block refresh, so that users do not need to refresh the page to see what's new. Not only is this useful, it also gives a interactive and modern feel on the main forum index.

It would be very useful to be able to watch a tag. This way a member can subscribe to discussions on content that interests the member. This would be a very powerful way to keep members interested, as they would receive alerts about content that interests them. This would also be very useful...

There is a lot of difference between the effectiveness of the XenForo search engine and Google. Google is simply so much better and effective in finding what you need on a XenForo website. IMO it's a difference of night and day. The main reason is that Google finds synonyms and paraphrasing...