datetime input with jquery.ui.datepicker and jquery.timep...
jQueryUI has a great date picker, and there is a great time picker based on jQueryUI.
Sadly, I haven't seen a great datetime picker yet, where the UI is simple and people don't need to click a dozen of times.
I'm not gonna to write a brand new one( I don't have that much of time, and I'm not a js master yet either ;), so I chose to combine the 2 js lib above, and seems that's good enough for me at least for now.
Demo is Here