You probably already know this, but fry the veges separately, leave them slightly under-done. add back to the pan when you've done the tomatoes, and it turns out much sweeter and tastier.
edit. Re. post about Ratatouille, havent worked out the quoting yet.
Anyone got any tips for a great ratatouille? It's my packed lunch of choice at the moment (usually with mackerel and cous cous)