Today was the launch of 1Password 4 for iOS, featuring a significant redesign and enhanced features such as search and folders. The app helps you maintain secure and unique passwords for pretty much anything and everything. It keeps your login details in an encrypted database, so that you only have to remember the password to access 1Password itself. So long as you observe good practice with the master password, your other passwords are secure. It's browser plugins and the mobile apps own built in browsers allow for fast login to websites and services.
The app will also securely store other information that you might regularly enter into web forms such as Credit Card details. I tend not to save my Credit Card details anywhere, and don't mind re-entering them when necessary but I can see how this approach is favourable compared with storing your details in multiple online accounts.
It will generate strong passwords for you, has Mac, Windows, iOS and Android clients that sync via dropbox (or in this latest version iCloud - though iCloud support has not yet arrived for the Mac). It's worth checking out, as is the Agilebits website. At the end of the day, the security of 1Password is governed entirely by how sensible you are with your master password - but the advantage of only having to deal with that password directly makes staying secure online much easier and will break the practice of password reuse.