Outlook is great, but there's one thing I'd really like to see in a future release: tagging support. Right now they have categories, which is ok, but not really what I want. The thing I don't like about categories is the fact that they show up for everything. For instance, I have about half a dozen categories for grouping contacts. When I'm looking at my calendar, I don't want to see those, but they show up. This could somewhat be resolved by adding tagging support to contacts, messages, appointments, and tasks. I still like categories, but tags would be nice.