I like to keep folders and files organised and systematically arranged in my computer. It's important that they're always in the same order so I can quickly find them without having to think about it. Not everyone is as OCD as I am when it comes to this, but those that are might find this useful.
The Mac has a specific order in which it shows folders and files when arranged alphabetically, or as it's called in the Finder in OS X, "sort by name."
Obviously, any files or folders that start with a letter will be sorted alphabetically. And those that start with numbers will be before these. For example, a file named "2012-08-15 something.pdf" will go before one named "something.pdf".
However, that's not enough for me. I want some folders to always be at the top, and some to always be at the bottom. That's where special characters are useful.
This is the order the Mac sorts characters (in Mountain Lion): space, underscore, dash, exclamation, question, at, star, accent, hat, plus sign, open bracket, equal, close bracket, pipe, tilde, numbers, letters, µ, π, Ω, and .
Space comes before the letter "A", so do most punctuation marks. I use a space for the 2 folders I keep at the top, an exclamation mark for my "action" folders, and the @ symbol for 2 folders that hold temporary files. The other ones before numbers and letters I don't use.
For the one folder I like to keep at the bottom I use the Apple symbol .
Note that some characters are reserved by the system for specific things and shouldn't be used. For example, files starting with a period are treated as hidden files by OS X.
By the way, here's how you get those 4 characters at the bottom: µ (Option M), π (Option P), Ω (Option Z), and (Shift-Option K)
My life is so hectic that my computer is like my haven of minimalism. And I like to keep it tidy.