The world’s largest aggregator of electronic books and articles, a non-profit offering over 3 million ebooks and audiobooks to read online or download. The World Library Foundation is a global coordinated effort to preserve and disseminate digital copies of historical books, classic works of literature, serials, bibliographies, dictionaries and encyclopedias in a number of languages and countries around the world. $8.95/yr.

A service that lets you look up the bitting codes for just about every lock manufacturer. Gives you the engineering diagrams and precise measurements for bitting to millimeters. Offers mobile apps where you can photograph keys and it'll decode them for you.

Basic subscription costs $10us a month.

A monthly subscription box of hacker stuff to build and experiment with.