For users lucky enough to run Jelly Bean 4.2 this is essential.
All information you need right on your lockscreen, be it missed e-mails, calls, weather alerts, you name it. An active community provides numerous extensions.
Check emails, alarms, weather, pretty much anything (there is a plugin for) on your lock screen with dashclock widget.
I use this with DynamicNotifications. Check out this useful app, there are tonnes of widgets for it in the play store
This app is a simple and clean widget to give you the time, weather, and more. Its greatest feature, though, is its huge catalog of extensions that give you the option to have this widget display pretty much anything you want.