As a computer science major, it is not surprising that I write a lot of small programs every day. From simple things like modifying some text input in some way (a chain of sed's), to writing my alarm clock, a twitter backup, and an ISBN converter. My journal search tool was written by myself, and that goes back quite a ways.
All of the programs mentioned above, however, are Bash scripts.
I'm actually a little sheepish about this. After all, Bash is not a real programming language, but just a way to automate a few administrative operations. There is no type system, no support libraries, no object oriented utilities.
I've thought about doing more things in python, but somehow there's a barrier to entry to it. I reasoned that since what I do is mostly with text, it's easier to read from files in Bash than in python (a single cat as opposed to open().read()). But really that shouldn't be a problem. The output might be an issue too, if I wanted things in nice columns and what not. But then instead of column or paste I would just be using printf or equivalent.
I was digging around Paul Graham's older essays, and I came across his one titled "Being Popular". It's about what he things makes programming languages popular. Most of the attributes in the essay don't describe the Bash script very well, except for the section on Throwaway Programs. And that, I think, is exactly why I use Bash scripts so often.
Because I'm using Linux, a lot of my operations are done on the command line. I don't just mean the crazy programmer things like compiling or system administration, but I mean every day things like moving files, writing essays, even reading a book. My volume control, in fact, is also a command line program (alsamixer; although now I have a keyboard shortcut for that and I rarely actually open alsamixer). Given that I'm in a terminal so often, Bash is practically always open for me.
It is precisely this always available attribute which makes me use Bash. As Graham mentioned, I don't want to write something, then wait for it to compile, then run it to see if it works. Bash works as an interactive prompt, and I can type the whole program in "one line" and just run that. More that that, I can test things a lot quicker in Bash than I can in C or Java. Just open a new terminal (Ctrl-N) and I have a clean slate to test if a certain line of my program does what it wants. Python, of course, is also interactive, but it is unfortunately not as easily accessible from the desktop. I have to type a full 7 keys (P-Y-T-H-O-N-(enter)) to get to the interactive shell, and this slows down the entire process.
So until someone manages to use python as their main shell, I'm sticking with Bash.