Metric.live - Real-time and advanced periodic alerts for Google Analytics.
Famous First Websites - Discover what popular startup websites looked like at launch
Statsbot - Connect your database, let Statsbot generate data relationships from your database automatically, and get your first insights in a matter of minutes.
Waybackpack - Download the entire Wayback Machine archive for a given URL
StatsGlitch - Insights and Alerts to grow your business. Powerful Google Analytics and Search Console companion.
Youtube++ - extension to show publishing date of related youtube videos.