What are the next planned space telescopes? We've had hubble for two decades. Its become the most famous space telescope, and lately Kepler seems to be running for the second place. Are there any more powerful, better telescopes planned for launch in the near future?
The James Webb Telescope is the next one on the launchpad that you might be familiar with.

Although there are a few differences that one ought to be aware of.  NASA has an entire program of telescopes to observe the universe, and many of them are designed for different wavelengths of light.  The James Webb is primarily designed for the infrared part of the spectrum.  While many people view the Webb as the successor to the Hubble, it would be more fair to say that it's really a successor to the Spitzer Telescope.  Hubble and Spitzer were both part of the "Great Observatories" program.  The Webb telescope is barely hanging on to funding, but so far the US hasn't managed to entirely abandon the program, science, or reality.