SL4A, Scripting Layer for Android, dramatically extends the capabilities of Tasker and your phone. It's pretty easy to get it working for pre-existing scripts such as the ones linked below, and you don't have to be a programmer to use them.
However, if you are not a programmer, you will find it tough going to write your own scripts. It's not for the faint-hearted, so be prepared to spend significant time learning how to use it.
If that doesn't scare you off, then dive in!
Note: The SL4A documentation contains lots of references to ASE. That's because ASE is the old name for SL4A, and it hasn't been changed everywhere yet. So if you see instructions telling you to copy something into the ase/scripts folder, it should really say sl4a/scripts.
Go here to find out more about SL4A and how to install it.
Then install the Python interpreter (at least) as described here. NOTE: Do not install Python 3. It is not backwards compatible with code written for earlier versions of Python. Install version 2.6.2 from the View menu. Or install this apk, which is the same thing.
Then take a look at the following examples of how to use SL4A with Tasker. If you need help with the Tasker interface, you can probably get it on the Tasker forum. But for help with a scripting language or the Android API, you'll likely have to look elsewhere, such as the SL4A forum or forums for the particular scripting language you're using.
If you do develop a useful script, please contribute it to this wiki.