Recently, I had the urge to do some HTML coding for a new website. Having used Eclipse before as an HTML editor, I decided to go that route again. I installed Eclipse Indigo on my desktop and then installed the Aptana Studio 3 plugin. This is cool. Next, I realized I would like to have the HTML development in a portable app. I've been a fan of www.portableapps.com for some time. They didn't have one listed, but a google search gave this version of Eclipse portable. I loaded this on my USB drive with no pproblem. Next, I tried to add the Aptana Studio3 plugin. I tried the "update site" way first and I coould never get it to load completely. Next, I tried to load a downloaded version. This didn't work either. So I gave up on Aptana Studio 3 and looked for alternatives. What I found was the web page editor plugin. This provides a decent html editor and you can test the code in an external browser. Now I have a development system which totally resides on my USB drive allowing me to take it with me to work and play. The disadvantage of the web editor plugin over the Aptana plugin is that the web editor plugin doesn't support ftp. I haven't arrived at the point where I need this yet. I'll let you know the solution when I do.
Addendum 7 Sept 2012: One issue you might have using the external run configurations is that the usb drive with eclipse may have different drive letter for different computers. To solve this difference between my home and office computer I changed the drive letter of the usb drive to Q: for both computers. Then all my run configs reference Q: and they work on both computers.