A curiosity of the notes application – it’s got a really ugly font. But it can be forced into a less ugly one on a per-note basis using an international keyboard. I assume the Market Felt font isn’t Unicode-complete, because if you insert a single (for example) Korean character into the note it’ll change its font to something more sensible that includes that glyph. And it won’t change it back if you remove the character.
This isn’t exactly convenient, and isn’t a system-wide setting. But I only have one or two notes on the phone, and I’m not willing to jailbreak it just to change the font. So I like my workaround.