FeedWind - FeedWind is the world's leading RSS widget, Facebook widget and Google Calendar widget - works on any website and is fully customizable
Feedly - The content you need to accelerate your research, marketing, and sales.
ViralSweep - Grow your fans and increase sales with sweepstakes and giveaways.
Superfeedr - Real-time feed API - RSS and Atom over PubSubHubbub and XMPP. Superfeedr pushes RSS feeds in real-time for both publishers and subscribers, with open protocols and APIs.
Juicer - Juicer provides a solution to aggregate brands' hashtag and social media posts into a single social media feed on their website.
Inoreader - Dive into your favorite content. The content reader for power users who want to save time.