In addition to just listing their password requirements, sites could provide a link or bubble help to a method of creating a "good" password. I like:
1) Pick a short phrase (e.g., "See Spot run.") but that connects to the site to provide some mneumonic value (so "See Spot hurl." might be for your vet).
2) Do some simple letter to number, symbol or punctuation substitutions (e.g., "S33 Sp0+ hurl.").
3) If you wish, squish out the blanks between words (e.g., S33Sp0+hurl.).
So we now have an easy to remember, eleven character password that includes upper and lower case letters, numbers, a symbol and punctuation.