Bucketlist.org - Log and catalog all the stuff you want to accomplish before you expire.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
List Challenges - Earn points for your life experiences. Find lists that interest you, and mark off what you've done.
Tagpacker - A free tool to quickly collect, organize, and share your favorite links.
Life Listr - ***AS FEATURED BY APPLE***
Diigo - Diigo is a powerful research tool and a knowledge-sharing community