Viral Marketing

Social Network Applications

Clearspring - Social distribution solutions connecting online publishers and advertisers to audiences on the social web.

ContextOptional - Builds presence for brands in social media, including Facebook and Twitter.

Momentum Design Lab - Smorgasbord of open social network and content API's.

Widgetbox - Learn more about finding, installing and developing widgets.

Tell-A-Friend Services

Free Tell A Friend - Add button on your website, visitors can automatically e-mail their friends about your website.

TAF Master - Your audience can produce additional traffic simply by forwarding your content to family and friends.

Tell A Friend King - Unlimited, powerful, viral marketing.

Tell-a-Friend Wizard - Tell A Friend viral marketing strategy.
 

Tell-A-Friend Software

Master Recommend & Recommend Pro - Makes it easy for your visitors to recommend your website to others.

Tell-a-Friend Pro - Tell-a-Friend system.

Viral Friend Generator - Tell A Friend software.

Viral Inviter - Traffic software.
 

Viral PDF eBooks

Affiliate PDF Brander - Software which lets you turn any ebook or report into a viral sales machine.
 
On The Fly PDF - Create pdf files on the fly.

Viral Document Toolkit  - Turn any document into a PDF.

ViralPDF - Brings full re-branding functionality to all your PDF ebooks.
 

Widgets
 
Clearspring - Social distribution solutions connecting online publishers and advertisers to audiences on the social web.

Gigya - Social optimization for online business.

Google Legacy Gadgets API - This is the legacy gadgets API developers guide.

Google Gadgets - Gadgets for your web page.

MuseStorm - Build better widgets and social applications.

Sprout Builder - Improves the way brands connect with consumers by creating apps across publisher sites and networks.

Transpond - Enables brands to easily create, publish, manage and track engagement with their content.

Widgetbox - Makes it easy, and fun to make widgets, Facebook Fan Page apps, and mobile sites to share with the world.