AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.
Product Hunt - A website that lets users share and discover new products
JSter - JSter is a community-driven catalog of the most useful javascript libraries.
Softpedia - A library of over 1,000,000 free and free-to-try applications for Windows, Mac, Linux and Smartphones, Games and Drivers plus tech-focused news and reviews
moreofit.com - Moreofit is the first (and best) website similarity search engine.
Filehippo - Filehippo is your key to opening files that Windows claims are "in use by another user" or simply "can't be found." Avoid the hassle.