I decided to go looking for something that could give me the ability to set window transparency in all of my apps. I love the fact that iTerm and the built-in Mac terminal support transparency.
Before I tell you my findings, let's dispel a common misconception: window transparency is *not* a useless feature. I have read several articles that dismiss it as such (as eye candy), but I strongly disagree. Having window transparency increases my productivity because I can see my inbox in the background of the window I am working in. Why do I care? I get *tons* of email everyday, some of it SPAM .
When Thunderbird alerts me that I have new mail, I feel compelled to drop what I am doing and read it. I have to know new information as soon as it becomes available. This is why my email response time is like 2 minutes, on average. Anyway, if I can see the subject of the message in the background, I will not stop what I am doing if the message is not important. Hence, transparency is a productivity boost for me.
Anyway, I came across Afloat, a Mac window transparency app. It is pretty good, but it only works with Cocoa apps (apps written in the Mac's native language). Examples include Safari, iChat, Mail, etc. Unfortunately, most of the apps I use are not Cocoa apps (Firefox, Thunderbird). But, I am running it anyway for now because it has some other cool features.
Afloat can also make windows "stay afloat" - they never drop into the background and are always visible. It's kind of cool because it turns down the transparency on these floating windows when they are not in focus.
Also, Afloat lets you drag windows around by grabbing them anywhere in the window - you don't have to grab it by the title bar.
All in all, I really like this program. I just wish it would work with my non-Cocoa apps.