There are lots of very good Linux editors included with most packages or freely available on the internet.  At last count I had over twenty small editor in my Linux system and about five or so full word processors.  That may sound like a little bit of over kill (and it is in a way) but it proves that Linux is all about personal choice.  You choose which editor you prefer alot of people like the vi editor and swear by it however I prefer to use emacs and vim (this one is very good). If you have just installed Linux or have had it for some time the chances are you have most of these editors sitting in your system and I bet you didn't even know you had some of them (I didn't until I was told what they were).  Here you will find information about some of them of course there are many more but these are just some that I know exist and have tried for myself.  If you know others let me know.

emacs, jed, joe, pico, tex, vi, vim (an improved version of the old vi (elvis) editor (my favourite))

These are all text editors and are very easy to use type man emacs or man pico etc for the manual pages on each one.
Other things you may like to try out are
bc, groff, info, ispell

bc is a great calculating tool that you can program and or use as is for calculations.  I will be writing more about this in the future as it is a very useful little program.