IIUC, you're talking about using what amounts to a user-managed password-generation schema. This seems like a weak (re: entropy) and ultimately very user-hostile approach to password management. Having known people who use such approaches, they still have to remember at some potentially distant time just what cocktail of fields they used in their password formula for this site. That is, the burden of password memorization remains but they don't gain much for their trouble.

I hear of such schemes from time to time but I've never seen them subjected to real attack analysis. I strongly suspect that these mostly generate surprisingly weak passwords.