Projekt, a popular Symbian OS outliner, is being ported to S60 3rd Edition. Asri al-Baker has been beta testing it and some screenshots are shown below. With Projekt, you can manage your lists, todos, mindmaps and shopping lists.
I second epo.fm. I feel I would use this software, though I would feel better and the app would look a lot more professional with more whitespace, clean lines etc or as epo.fm said, incorporating your current theme. I appreciate it is an early beta and cosmetics can be done at the last minute.
The colours, fonts and general appearance of Projekt is customisable. I have used Projekt for years on Series 80 (9300) and UIQ 2 & UIQ 3 and I feel it is the best app out there to manage notes and stuff.
As this is the very early beta, there are still lots to be improved like linking to calendar entries, linking to todo items as well as linking to files, not to mention, linking to contacts.
If you want white background, you can adjust it from the setting. However, regarding the theme, I cant answer that because theme background makes the information less visible IMHO.