Diigo - Diigo is a powerful research tool and a knowledge-sharing community
LinkLocker - LinkLocker is a lightweight bookmarking service with an emphasis on privacy.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Marketing Optimizer - Optimize conversion rates, increase lead-to-close ratio, and resell leads easily. Includes complete WordPress integration.
Linkman - Linkman Pro allows for managing large amount of URLs in its own database.
Instapaper - Instapaper is a simple tool to save web pages for reading later.