Based on the impeccable behaviour of my heavily used Olympus D-490 zoom (2.1MP) over the last 3 years I reckon that the 3.2MP Olympus C-740 ultra zoom is one of the current sweet spots at an estimated $449 - takes filters too.
If 2.1MP is enough for detailed clinical photos (and it is) then 3.2MP should be OK for almost anything apart from real pro stuff.