Build us a mech and pilot for a non-military application. We love those railguns/ rocketpods/power fists too, but in a world where we could conceivably build hard-suits, exo-frames, mecha, etc. then letís assume we could find a use for them that doesnít involve blowing each other up.
It is 2105 AD. Mechs and exo-suit technology have been in development for years and are now finally beginning to hit the streets in large quantities. One of the mechs created in this wave of growth is the 3Z CL3NR exo-suit. It's purpose is to climb the sides of skyscrapers to clean windows. Special suction pads in its feet create a vacuum between the feet and the wall, allowing the exo-suit to hang suspended to the wall (ala Spiderman). From this position, it can deploy its inbuilt sprayers and cloths to clean the window. By releasing the suction on one foot at a time, it can then slowly climb to the next window to repeat the process.
Here is my building facade. The style was largely influenced by Mr. Xenomurphy's techniques in Spider-Man vs. Green Goblin. Even though many newer buildings will have been developed in a hundred years, Not everyone is willing to pay the money to move their company into one, so good old fashioned skyscrapers are still a normal feature of cityscapes.
Here is the window cleaner with an old-fashioned spray can (you never know when the fancy new hoses will malfunction and the job must be finished).