Mailbrew - Automated email digests from Twitter, Reddit, YouTube & more
Reddit List - Tracking the top 5000 subreddits
Taco Digest - Customizable personal email newsletter created from your favorite sources.
Reddit Check - A tool to check if a URL is on Reddit and going viral
Blogtrottr - Track RSS feeds and send updates to your email inbox.
Suggest Subreddit - Recommends you subreddits based on your subscriptions