It's not a bad idea, but there's a few problems:

1. I would 100% forget which symbol goes with which site.

2. The length I choose for my password may be too long/short for a given site.

3. Some sites require special symbols; some sites forbid them. Now I have to pick out my symbol based on the site's requirements, not ease of memorization.

One solution to the site restrictions regarding symbols would be that you generate a non-symbol password, and a symbol substring. You add the symbol substring when you know that the site requires symbols (or if the non-symbol password fails).

I use passwordcard too and when I get a site that clashes with my algorithm, I give them one of 4-5 passwords that I used to reuse everywhere before I implemented the scheme. I have a 6-symbol password, a 10-symbol password with special characters, sure they've also been used on a dozen other sites but if their super special requirements make me extra secure who am I to blame them, I'll use my super special passwords that fit :^)

I could use a password manager but I don't want to be dependent on one piece of software, there's too many failure modes. It's already bad enough that all my accounts share a limited set of email addresses.

The main issue I have with schemes like this is that there's no repository of global identifiers for websites and services. I can build a password for blizzard.com, starting from say "bl", then I forget about it and five years later their website is now activision.com, and I wonder why I can't log in with a password built from "ac". It's a minor issue since password resets are a thing and rebrands are rare but still..

We need a website like http://plaintextoffenders.com/ but for the ones that have hurtful password rules.

Ah good yes, please do generate all of my passwords on the server side and then send them via HTTP.

The site supports https