Plain .txt is a very bad choice for an e-book. Let me say that again. A
very bad choice for an e-book! Instead, here's what you can do: change the .txt extension to .html and use basic tags like <b>, <i>, <br>, <img>, etc. You can still edit it just fine with whatever text editor you prefer as long as you don't use anything too heavy like Word or even Wordpad, because they add a lot of unnecessary stuff.
Of course, if you really (really??) wanna stay with .txt, you can probably use ASCII art or something... But the alignment would depend very much on the used font and it's not a very good choice for re-flowing formats (ePub, Mobi). They'll also get fragmented like hell on smaller screens.
http://www.google.com/search?q=ascii+text+generator
Code:
***
=== Chapter Title ===
-------------------
CHAPTER TITLE
-------------------
-+-
-_-_-_-_ Chapter IX _-_-_-_-
_ _ _ _ _
/ \ / \ / \ / \ / \
( T | i | t | l | e )
\_/ \_/ \_/ \_/ \_/
_____ _ _____ _ _____
/__ __Y Y__ __Y \ / __/
/ \ | | / \ | | | \
| | | | | | | |_/\| /_
\_/ \_/ \_/ \____/\____\
_|_|_|_|_| _| _| _|
_| _|_|_|_| _| _|_|
_| _| _| _| _|_|_|_|
_| _| _| _| _|
_| _| _|_| _| _|_|_|