Reddit is a massive website that offers groups for any topic imaginable. If you want to share your shower thoughts, are a fan of 70s design or like to look at pictures of lazy cats, then you find a group for that on the site.
Chance is high that Reddit has groups for topics that you are interested in. It is rather difficult to find those on the site. While you could use the site's search for that or try your luck by by adding topicsw of interest to the url in the form reddit.com/r/thatsgreat, it is not the most comfortable thing to do.
Reddit Metrics is a site that highlights what is popular and trending on Reddit right now. You can use the site to list the most popular groups on Reddit -- hint it is not cats -- or check out trending charts instead.
If you are interested in a particular group, you can enter its name in the search at the top to get detailed stats about it.
You find listed the subscriber growth over time of it and the total number of subscribers. In addition to that, its rank is listed and milestones based on past trends. Milestones include passing a certain number of subscribers or being a trending group on the site.
The stats are mostly useful for moderators or admins of the group though and not users interested in the topic.
The front page of the service lists the fastest growing reddits of the day, last week and last month, as well as similar information for new reddits, new reddits that are trending and non-default reddits.
Those information alone can be valuable as you may use the information to discover new reddits that you did not know about before.
Note that there is no distinction between regular and adult groups so that it is best if you don't use the service at work or in public locations.
While the site itself displays textual information only, it does link to the groups on Reddit which means that you can click on them to be taken to that group.
Another interesting option provided by the site is its comparison feature. You can compare up to five subreddits to get each group's subscriber count visualized over time.
You can use it to find out which group is more popular on Reddit. Is Firefox or Chrome, Android or iOS, or cats or dogs more popular? It is important though that you pick the right subreddits for the comparison as you can only compare groups but not topics of interest (you cannot compare ios, iphone and ipad with android for example).
The site lacks direct links to Reddit. If you want to visit a group on the site you either have to open it manually or open the statistics page of it on Reddit Metrics to do so.
The second thing that is less than ideal is that it does not highlight NSFW groups.
Now You: are you a Reddit regular? If so, which SFW groups are you subscribed to?