The idea behind this site is that you group items using the colours on the left. For example, when I'm going shopping I group all shopping list items in blue. You can click an item to strike it through, which I've been using as a sort of "done" state before deleting the item.
I've been using this tool a lot lately, and it has helped me pay attention to the finer details at work.
http://www.listabulous.co.uk
Code for the site is here: https://github.com/AndrewVos/Listabulous