TextWrangler, a freeware tool from Bare Bones Software, is a great text editor. It has a panel for accessing all your open files, lets you run scripts and capture output easily, change file encoding, does syntax highlighting, offers to unlock files you don't have permission to, and does everything you'd expect from a general-purpose text editor. [And no, I'm not affiliated with them.]
Of late, I've really enjoyed the fact that on the command-line, you can type:
and it'll open it up the file. Better still, you can pipe to it:
ls /Applications | edit
where there is a lot of output, this is really a nicer way to go through it.