This thread is worth of resurrection
You can program in soooooo many languages it will make your head spin....... and NO need to buy anything to do it

Thats the beauty part
http://www.usalug.org/phpBB2/index.php?c=3
Some of the languages you can program include:
Bash (and several OTHER shell scripting languages)
Awk & Sed
Perl
Python
PhP
Ruby
Java
C
C++
and that's not all of them

Compilers are usually already installed by default for c and c++ , and downloading and installing compilers for java and others is relatively painless. If you ever wanted to learn programming.... Linux makes it easy to get started