Here's an interesting demonstration of how much more powerful robots are becoming. A group at Stanford has produced tiny robots that can lift, while climbing up walls, more than 100 times their own weight---and one that can drag a weight 2,000 times heavier than itself. As one of the engineers involved put it, that's "the same as you pulling around a blue whale."
Here's the story in New Scientist.
The secret turns out to be gecko feet and other innovations drawn from biology:
The secret is in the adhesives on the robots' feet. Their design is inspired by geckos, which have climbing skills that are legendary in the animal kingdom. The adhesives are covered in minute rubber spikes that grip firmly onto the wall as the robot climbs. When pressure is applied, the spikes bend, increasing their surface area and thus their stickiness. When the robot picks its foot back up, the spikes straighten out again and detach easily.
The bots also move in a style that is borrowed from biology. Like an inchworm, one pad scooches the robot forward while the other stays in place to support the heavy load. This helps the robot avoid falls from missing its step and park without using up precious power.
Here's a YouTube video of the little badasses: