An iPod Touch has various apps available (like DocumentsToGo) where you can create documents to save notes, etc. That's what I use now, instead of my dead, beloved Sony Clie PDA. I have an iPad, too, but it's too large to carry around everywhere. If you have a smartphone, most have apps like that available.
I was bemoaning the lack of Graffiti for writing notes just the other day - it seemed to be faster, to me, than using the virtual keyboard.