*EDIT* Yes I realize there are "easier ways of doing this now. But personally this is easiest for me. I may add onto this to show other ways it can be done.*EDIT*
This tutorial is only for Mac OS X for a guide on how to install the apps from a windows computer please see here:
http://forums.palmpreforum.org/homebrew-apps/191008-simple-how-guide-getting-homebrew-apps-onto-your-pre-after-1-0-4-a.htmlInstalling homebrew apps on your Pre through your Mac is very simple.
Disclaimer: Homebrew apps are NOT approved by Palm be careful what you install and only install from trusted sources.Step 1: Download and install the Palm Pre SDK for Mac from
http://developer.palm.com/Step 2: Put your Pre into developer mode. Type upupdowndownleftrightleftrightbastart into universal search a "Developer Mode Enabler" icon will pop up tap it and turn on developer mode, your Palm Pre will reboot.
Step 3: Once the Pre has rebooted plug it into your computer through USB, select "Just Charge"
Step 4: Download the homebrew app that you want. There is a big selection at
http://forums.palmpreforum.org/homebrew-apps/Step 5: Open terminal within Mac OS X. If you don't know where to find it go to Applications-->Utilities-->Terminal
Step 6: Type palm-install SPACE then drag the .ipk file into the terminal.
It should look something like this:

Step 7: Press enter
This is what it should look like:

The green splotches are jut personally identifying numbers I removed.
That's it you are done!
Look on the first page of the launcher near the bottom there is your new app.
Simple as that.
Cheers.