One time when I was bored, I made an Energy/Energy Blaster with the sole purpose of knocking everyone back. So when I unlocked Power Push at Level 18, I fully spec'd it with Knockback recipes and enhancements and went into Atlas Park. I then found as many lowbies as I could and would use Power Push and send them flying across the map. Sadly I have no video since I didn't have FRAPS at the time
I did this too with my first character, the magically-fueled MAGI-1 android. Happiest moment was coming back at level 50 and punting those Hellion punks that killed me at level 1 over City Hall.
Most unique characters... phew...
First that comes to mind was Longbow Assault. I always liked the Longbow as being the army that was on the good-guy's side for once, but I was always disappointed they didn't show up more around Paragon, especially at higher leveled areas (not including PvP). So one day I made one! I was a Blaster fan to the max, and did my best to recreate the costume pattern to the best I could, gave her Assault Rifle and Devices (though had it been open at the time I would have used Beam Rifle/Martial Combat) and set her loose!
She was a covert ops specialist, preparing areas with mines, caltrops and gun drones before luring enemies in by sniping their leader with a well placed shot. Despite that, she was also uncannily good at kicking down doors and lighting the area up with automatic fire, using her prototype rocket boots to keep her out of reach and mobile.
I had a ton of fun RPing as a Longbow operative, especially when dealing with the Vanguard or fighting in PvP.
However, most of the more unique heroes I encountered were made by my dad, particularly two of his favorites:
Surtyr, based on the King of Fire Giants in Norse mythology, with a Broadsword and Rgen (don't ask me why), was a towering red giant with coal-black face and hands, and eventually heavy armor.
Then, there was Jupiter's Eye, a Gravity/Storm Summoning Controller based on the idea of a gaseous being from Jupiter being accidentally captured and returned to Earth.