BPasswd is a strong password generator. It derives passwords from a master password and a usage-specific "salt". Since BPasswd is aimed at the web, the "salt" is usually something site-specific such as "github", "amazon", "google", etc. In other words, you get to reuse one (or a handful) of passwords, but end up with a unique password for each site. Best of all is that you don't need to carry around some key file or trust a third-party service like you'd do with a password manager.
The web version is available at: https://u.alexhornung.com/bpasswd/
For more details, check out: http://www.alexhornung.com/code/bpasswd/