[katbyte]

There are strong/long passwords that are easy to remember:

%Thisspasswordd1s1nhonor..ofmy246catSS!!

http://xkcd.com/936/

having a 20-30 character long password is fairly easy, it may not be 100% random, but (correct me if i'm wrong) a password that long with just a handful of random extra letters and numbers is going to be rather easy to remember and probably going to be just as had to brute-force.

[DanBC]

You have to be careful when adding some random characters, because most cracking software includes dictionary mangling options.

Thus, option 0ption opt1on etc all get mangled into a wordlist, while )*&HD@IHU don't. Yes, it still increases difficulty, and they are much easier to remember, but people need to be careful.