Looking at the list of groups for interesting things I was struck how some topics have a large number of groups that bury the more niche, but still interesting groups. This makes those laborious to find.
If it were possible to exclude some topics while listing groups it would be easier to read through what remains. Conversely, if your interest is one of these group clusters you can read through just that.
Obvious candidates so far:
Trains/ railway/railroad of all types and sizes.
Amature/ ham radio
Dolls and related (doll clothes etc)
All things fabric knitting/quilting etc
Disability related Blind etc
Spirituality Inc religion/paranormal etc
Graphic arts other than incredimail
Arts other than graphic etc listed elsewhere.
Metal, wood and plastic working- casting/lathes/milling machines/3d printers/tools/machine shop etc
Cooking/ food related
Brewing and distilling
Literature not listed elsewhere
Science not listed elsewhere
Themed friendship groups, veterans, old co workers, local community etc
Strictly local, family networks etc.
Other not listed elsewhere.
I'm sure there are more but that's my first impression.
Group owners could be asked to choose one category to belong to. This will resist the erosion of intent if groups were entered in multiple categories. Choose a core identity.
Eventually group owners could request the addition of new or sub categories. Second level to avoid delaying the first level.
This will make it easier for potential members to find groups of interest. Particularly for eclectics and synthesists who don't always know what they're looking for until they find it.
A Boolean search of categories to include or exclude when sorting the list of groups would be ideal.
The recent groups is a useful sort but swamped right now. The existing sorts should be able to be applied to the results of the category sort.
The top five are all pretty big the rest are in random order as they popped into mind.
I hope this will happen as soon as possible.