I just love Gmail labels. I have lots of them, over two hundred. Every person has a label. I also have several special labels, like personal and work. I use them to label mail that I have read but can not respond at the moment. I use those special labels a lot. Labels are sorted alphabetically, so those labels are at the bottom (personal, work). I use a simple trick to move them to the top of the list. I add dot to the beginning of label. Now personal is .personal, and work is .work. You could use another character, but I like dot. It is small and useful.