pwgen generates random, meaningless but pronounceable passwords. These passwords contain either only lowercase letters, or upper and lower case mixed, or digits thrown in. Uppercase letters and digits are placed in a way that eases remembering their position when memorizing only the word. .

Install pwgen with the button below:

e.g.

sudo apt-get install pwgen
pwgen

apg

APG is the Advanced Password Generator. The software is used to automatically generate new passwords for whatever use you feel like putting it to.

Here are some key features of "APG":

• Setting maximum percentage of special characters
• Setting the length of generated passwords
• Grouping characters
• Setting a number of passwords to generate
• Setting a random seed file
• One Time Pad Generation
• Printing how many passwords it generated in how many second

To install, run this command:

sudo apt-get install apg

Install and using Apg with this help guide

Aberystwyth University has a pretty hardcore mnenomic-passsword generator.

http://www.aber.ac.uk/cgi-bin/user/syswww/gw/mnemonic

Generates evil password like this:

<1n255s4    Lisa's first newt zooms Fife's fifth shrewd four.
t6pnjsnv    Tony's sixth padlock nags John's spectacular number vainly.
fqyumdc8    Fiona's quadrilateral yucca understands Murray's dormant calculating eight.
ee6pk3cm    Eve's egocentric six ponders Ken's third cagey magazine.
q1giwn?n    Quentin's first galaxy improves Wyn's nondescript question mark nastily.

Interesting work. You might like to email their sysops to see if the script behind it is freely available (and if it's not, whether they'd consider GPLing it)

Edit: Looking at the output a little more cafefully, this would not be hard to code. You'd just need several dictionaries to feed it.

Try the password card. You carry it in your wallet and you remember two symbols and a color.

You read the letters / numbers between the symbols along a color line, or make up any algorithm that you can remember.

The site generates a random card for you.

http://www.passwordcard.org/en

The results are more hideous even than apg or pwgen (even with the -s option set), but this is more fun:

head -c 8192 /dev/urandom  |   strings --bytes 8 | sed 's/\s//'

I suspect your use case if different, but this kind of thing is useful for shared secret keys, and other kinds of passwords that you don't type in very often.
To get a larger selection, pass more bytes to head, and to get longer password result strings, modify --bytes in strings (which gives a minimum length). the sed expression strips out strips out spaces and tabs (represented by \s).

However, you will at some point probably appreciate applications (like pwgen, KeePassX or LastPass) that give you an option to avoid easily confusable characters, like 1 and l and I . These can look like 1Il or 1Il or worse. You would want to use an option like this if you are resetting someone's password or giving a one-time passkey that needs to be communicated.

Stil, pwgen put gives this caveat in its man page, describing its -B option:

   -B, --ambiguous
          Don't use characters that could be confused  by  the  user  when
          printed,  such  as 'l' and '1', or '0' or 'O'.  This reduces the
          number of possible passwords significantly, and as such  reduces
          the  quality  of  the passwords.  It may be useful for users who
          have bad vision, but in general use of this option is not recom‐
          mended.

This is nuts, of course. You probably know when this is useful or not. And it's certainly better than using 'Pa$$w0rD' for everything. If in doubt, create a longer password, or pass your generated password as input to another generator, or use multi-factor authentication.

I use mkpasswd. While technically it is used to encrypt a password for use inside an /etc/passwd file, it also gives nice strings of characters suitable for passwords.

No mnemonics, but pwgen is pretty straightforward.

I use apg -- sudo apt-get install apg

Keypass has a built in password generator. Generate your new password and remember it with the same tool.

SuperGenPass is a bookmarklet solution originally intended for website logins, but it can easily be used for applications, too. It uses a master password plus the current domain name (or application name, if you like) to generate 10-character passwords like lCY9gjiDtF. It doesn't need mnemonics because it can one-click auto-fill the password box, and allows copy/paste into other applications too.

I keep a bookmarklet in each of my browsers, and on my cell phone (works offline, too!). It's very convenient. If you're "brave" then you could even hardcode the master password into the bookmarklet.