IIRC there was a post by Steve Wozniak here a few months ago where he stated he still occasionally gets ideas for how he could have improved the code for the original Apple computers.
Edit: Found one article that quotes Woz on that: http://www.cultofmac.com/302087/38-years-later-woz-still-thi...
Makes one wonder what kinds of fantastic things we might achieve with todays' technology, but probably never will, moving on to build tomorrow's technology instead.