"Robust" or "strong" passwords...

Choosing good passwords

"The safest solution for choosing good passwords is to use a randomly generated or seemingly random password that:

* Is at least 6 characters long, and longer if possible.
* Contains a mix of upper and lower case letters.
* Includes numerals, special characters, and punctuation.
* Is not based on any personal information.
* Is not based on any dictionary word.

Examples of strong passwords include:

* De2#vu
* 5sd$oiP
* er89TI
...
Some security experts recommend using a password based on a mnemonic, such as an easily remembered phrase. For example, take the first letter of a each word in a phrase, then add a few special characters or numbers to it. For example, "lend me your ears" can become "lmye4%". "To be or not to be, that is the question" can become "2Bor!2b?". "

More info at: Wikipedia's password strength article