Add more display options
Resize fonts, icons and tabs, so more tasks can be displayed (only 5 on GT540) => better synthetic and comprehensive overall view
Open EXISTING notes as READ ONLY to save screen space. An option to open read only (with an edit button) would allow considerably more information on screen at once and I think it would be a huge improvement. When a field is touched, you could make that field directly editable or switch to an edit screen with the cursor in that field. I don't get a keyboard until I touch something anyway so it would not detract from usability at all and in fact it would greatly enhance usability.