So it seems like tags are the main things here, somewhat similar to communities on that site which shall remain nameless. Although I've also seen a fair share of tags being used like hashtags of twitter, but majority are used as the former. In that regard, the URL for accessing tags is kinda awkward and unfriendly: "/tag?id=sometag". If it were simply "/#sometag" that'd be much better, no? Apart from being easy on the eyes it'd become easier to discover, or even just revisiting, tags more intuitively.
Even better would be being able to browse multiple tags and those tags alone, so you could browse hubski.com/#science#physics#technology without all the other things.
#categorizationIsAwesome! #optionsNeverHurt