It's not often I go for stand alone lockscreen themes, but LS Qclock for iPad simply blew me away with its cool, clean, and simple look. Best of all it fits with most other themes I've tried it with (the screenie below is combined with iNitsua Twilight 3volution).
The text panel in the middle of the screen updates to provide the current time in words. Very cool.
Have a look for yourself and why not give it a try? It's a free theme in Cydia right now!