One of the more interesting features of Sublime Text 2 was the ability to view a file in two places at once. I saw this in a video tutorial on Lynda and wondered if it was possible to do in Eclipse also.
This becomes VERY useful when editing HTML files where CSS/JS declarations are in the header and the content is in the body.
Sublime Text 2
Since I saw this feature here first, I'll write about it Sublime before Eclipse.
Open up the file you wish to edit. Then click on File > "New view into file".
My old trusty Eclipse. Slow and hefty, but it's the Swiss army knife of development for me.
As before, open up the file you wish to edit. This time, click on Window > "New Editor".