Tabs in applications are the new thing. They’re hip, they’re cool, they’re useful to organize and save screen space. They’re the closest thing you can get to “black” other than web 2.0. My biggest irk is that application makers can’t seem to come up with a standard for the keyboard shortcuts that will cycle through tabs.
Adium is an example of a great application that gives the option to choose how tab cycling should work:

Considering how varied this process is, I think the programmers/designers of that project stumbled upon a great idea that more developers should implement. There are so many good reasons to do this. It gives the power user a choice without going in and editing the resource file. I don’t want to do this each and every time I update your application. Let me save this in the preferences and be done with it.
I have cycled through a few preferences for the way keyboard shortcuts should work since I started using OS X. Recently, I settled on the Safari method for cycling tabs:

Every time I download an application that does not utilize the Safari method, I go through the process of manually modifying the resource file for the application, customizing the keyboard shortcuts as I see fit.
The following applications utilize methods other than the Safari method: Transmit, Firefox and Camino. I can’t think of anything else off-hand but especially when it comes to browsers standardization is vital!
I can’t give Firefox a really bad rap when it comes to tabs though, simply because Firefox has a feature that I really miss: The ability to go directly to tab 1, tab 2, tab 3, tab 4, etc. simply using the option + 1 shortcut. I wish more developers would do that.
My final thought on this is creating an application that would easily allow you to modify the keyboard shortcuts of any application in OS X would be really useful and might even make enough to support a small software company. Being a developer though, I’d rather just see developers allow for choices in their applications. In that sense, a free framework allowing developers to implement customized keyboard shortcuts in their application might be useful.