This is my review of the application CodeRunner. This is the application I use when I am scripting etc on my main iMac at home.
If you do select a language (default list below), then you have full colour coding when you are typing. You can fully test your code as well from the application, you don't need to exit this and run from the command line for example. You also have the option for a "Custom Run" so if you are testing a script that can accept different inputs, you can pass them to it directly from within the application as well.
It has tabbed editing, so you can have multiple scripts open at any time, which is very handy if you are copying snippets from one screen to another. If you do click on a script from the sidebar, it automatically loads this into a new tab automatically. I have this setup on my Dropbox folder where I store all my scripts, so it is very simple when I need to edit a file.
You can easily create/edit templates to save you typing out snippets of code over and over. There are other good features in the application, I recommend you look into it. The application is has a very small footprint, it only takes 1.5Mb to install, so you don't need to worry about it consuming lots of hard drive space.
This is a great application, it is available on the Mac App Store, currently this is priced at £6.99, I remember a couple of months ago when I downloaded it it was only £2.99. If you are looking for a good application to code in, then I recommend this highly.
I am always looking at ways to improve, and so I am always interested in feedback so feel free to add any comments to the site, or you can email me here.