Most of these are characters and designs from approximately 10 years ago- a few are older. Redrawing these characters was a lot of fun- and the Redraw challenge can be a great way to combat artist block. The thinking is done for you- all you have to do is either redraw the character faithfully in your current style, or redesign the character and see how your tastes have improved over time.
If you think you've made no artistic progress over the years, I challenge you to try redrawing and redesigning old characters with your current artistic sensibilities. Redesigning can be great if you're going through an artslump- most of the work has been done for you- you just need to focus on improving the design. I enjoyed this exercise so much I did several different iterations, and will probably do further variations on this exercise.