My main use for Textmate is in conjunction with Latex. I have two screens, one for the code and other for the .pdf render. I am using Lion and the Full Screen is a resource that interests me. I tried some "solutions" and I will describe them here.
Isolator: It is nice, but if you use a two screen environment it is not satisfactory. If I use the isolator in the screen with code, it will blank the other screen with the pdf also, so I can't see the pdf in the other screen. Isolator would be fine if one can use it individually in each screen.
EGOTextMateFullScreen (Full screen for Lion): As I told in an earlier post, you cannot center and resize the text mate window. Besides, the other screen is also affected and the pdf disappears.
Textmate-Fullscreen-Plugin:It is the best until now, because you can resize the window and it does not affect the other screen. The problem is that the background is not 'blanked'. It would be perfect if this plugin also turned the background of the textmate screen into black, just like in Pages.
While I was writing this post I realized that it is possible to adjust Isolator to affect only the main screen: defaults write eu.willmore.isolator HideOnMainScreenOnly 1
...
So with this option in Isolator, I recommend Isolator + Textmate-Fullscreen-Plugin
This combination allows you to resize the Textmate window, it leaves the second screen with the pdf unaltered.
http://dl.dropbox.com/u/11537571/isolatoandfullscreen.png
The only problem is that everytime you get out of the full screen mode, and you get back to full screen you have to resize the window again.
You can use only Isolator, but this way you will always have the mac menu in the top of the window.
http://dl.dropbox.com/u/11537571/onlyisolator.png
Best, S.V.