I use TextWrangler as my all-purpose text editor. Powerful, but free... 🙂
As for hex editor, I don't know, but I'm pretty sure you'd be better of with one good text editor and a good hex editor instead of some application doing a half...good job on both... 😉
TextMate 2.0 will be a free upgrade to anyone who purchased 1.0, so there's no penalty for buying it now. I would like to second the recommendation for TextMate, though, it's an incredibly powerful text editor.
SubEthaEdit is also nice as it allows for real-time, collaborative editing (if you need that kind of thing).
Smultron is a decent freeware editor (although the icons are crap).
...as for a hex editor, I'll be of little help to you there.