I haven't found anything like this in App World. I too would like to see the entire duration of each appointment blocked out when in Day View. The idea of a single bar blocked off with a vertical line down the timeline looks like a lazy solution on the part of whoever coded the calendar app. Obviously it's not, but it seems like they said, "Ah, this is good enough. Just leave it like this." I'm sure RIM had reasons for making it like this, but I'll be darned if I can figure them out. Has this view changed in OS 6?
The other thing I've been PINING for is a new calendar view called Grid View. The week-at-a-glance view like paper date books. Palm had this on their Treo phones natively, and later when they dropped it users could download DateBk from Pimlicosoft to get it back.
This is a great view for folks with a level of scheduling that includes one or two appointments per day. It lets you quickly assess your week and gives you a visual feel for how things are shaping up.