Reddit Metis - show stats and analysis of a given reddit user
Subreddit Stats - Statistics for every subreddit.
FrontPageMetrics - Daily updated statistics for every subreddit on Reddit. Top subreddits, new subreddits by date, all subreddits, trending subreddits, plus more Reddit stats
RedStatz.com - Reddit Website Statistics
Redective - Find information about Reddit users
Reddit List - Tracking the top 5000 subreddits