Chetbox has a Python S60 based freeware Notepad text editor for Nokia S60 3rd Edition devices (as well as S60 1 and 2 Ed).

Features of this software are:

File browser for opening/saving and more.
Maintains a list of recently opened/saved files.
Cut/Copy/Paste.
Settings panel to easily change options.
All settings are saved and restored when next using EasyEdit.
Change screen size and font.
Set encoding of files read from/written to disk.
Search within a file, including find and replace.
Supports windows and unix style text files.
Support for line numbers.

To install this software, do the following (applies to S60 1st, 2nd and 3rd Ed)-

1) Download and install Python for S60 from Nokia for your device
2) Download and install the SIS package for your version of S60

S60 1st Ed- http://chetbox.googlepages.com/easyedit_1.44-1st-edition.sis
S60 2nd Ed- http://chetbox.googlepages.com/easyedit_1.44.sis
S60 3rd Ed- http://www.dnastase.info/pys60/easyedit.sis