(this comes across as a product plug, but its well worth it - I try to give credit where its due) 

As time goes on many of us find ourselves in knee deep in Password Hell.  You know how it feels, you have about a gazillion web sites which you have signed up for at some point in time and you have no idea what credentials you used for each.  Many people that I talk to start to consolidate their passwords to a single value, or a set of values and use them across all their logins.  Ask any security guy about the implications for that and he is likely to slap you upside the head.  Not to mention this doesn't play well with those sites which require fairly complex passwords and have policies set which you need to keep them changing after X number of days or whatever.  Another way which I found myself doing quite allot was trying the password reminder function prior to registration.  What a mess ...