I have the copic marker app and a list of copics I own in iPhone reminders program yet this is my favorite log. 

  
I can look and at a glance see what I’m missing and how it interacts with the colors around it. Everytime I buy a marker I just fill in the box and I know what I need next. It’s a great tool and really aimed at those of us who are visual learning people. I have to see and do before I really know something. 

Here’s a link to print your own. 

Click to access 358_Blank_Color_Chart_ltr1.pdf

(Btw, as of the date of this post, I need more E’s before the convention in April cause steampunk is the theme.) 

For artists and those that love an artist, I go to the blicks art store in Dearborn, MI. They have a large selection of copic markers and an online store where you can also get gift cards. The people are usually helpful even when you get the occasional art snob.