So, busy yesterday looking at twitter lists. Looks like you can have 20 lists which are like sub accounts - I am using these lists to put twitter contacts into groups - this will take some time, but not that long as I have around 5000 on @lemonknickers and a couple thousand on several other accounts. The list names are changable, I might even merge my accounts as the reason I opened up multiple accounts was to track different subjects - not to spam!
Most of my current lists are private, but I have the directory - of products and services open, and cool people - which are people that have my kudos!
open lists - that are still being sorted - on an ongoing basis: