I use 'retro clock' and 'retro date' widgets on the top of my main homescreen. Tapping the date links you straight to the calendar and tapping the clock links you to your alarms. Both are very nice and are the flip style like the old alarm clocks back in the day.
For weather, I use the Weather Channel widget, which displays the temp and weather on the home screen, and if you set a place for home, puts the temp in the notification bar. Very useful app and has a lot of information as far as same day, 36 hr, and 10 day weather reports, plus can handle multiple locations.