When things get virtual we usually start by mimicking familiar physical world. We have mailbox, folder and envelope icons, "old phone" ringtones, and lot of other UI metaphors inspired by things now obsolete. Nothing wrong with that, as long as by doing this we do not limit our creativity. Take a look at this picture of Pebble watch:
In pebble argot this is called "watchface." This is a particularly popular one and there are dozens of variations of it in the Pebble store. The problem shown is that sometimes date "window" (at least this is what it is called on mechanical watches) is obstructed by watch hands and you could not tell the date. There is nothing you can do about it in old style mechanical watch, but on Pebble you can, for example, move the date window position around to make it always visible.
We use google calendar at our company, and I have some of my colleagues calendars shared with me. This is very convenient as I can check their availability right from my phone when, for example, scheduling a meeting. What I miss is a very simple feature. If I am about to call somebody and his calendar shows that he or she is in a meeting right now, I would like my phone give me a quick warning:
"Alex seems to be in the meeting with Joe for next 40 minutes. Are you sure you want to call him?"
[YES ] [no] [Remind me in 40min]
If somebody would write an app doing that I will be one happy user!