Ha, funny. Just stumbled across a new application called TexWriter. Most interesting feature to me is having the PDF display within the same window as the LaTeX code. Instantly reminded me of a quick UI-mockup I did some five years ago.
When I presented this very idea to members of a well-known LaTeX-mailinglist, I was told that showing output next to input was like “totally against the rules of TeX” etc.; would’ve done it anyway, if we had found the time, he.
So, best of luck to Jakob over at DeliciousCode! As one fellow poster put it way back when: Keep it up, I think you’re on to something here…