I prefer to use SimpleNote, because my notes are available anywhere via a web interface. Also, many text note apps (like Nebulous Notes mentioned above) save to Dropbox, which is also available from anywhere.
I bought an app called CloudClipboard but I found I don't really have a use for it. It works between iOS devices, and there may be a Mac version too, I don't remember. The advantage is that you can also copy images and web clips. But I find that mostly I just want to save bits of text and urls when I'm at work, to use them later at home, or transfer text from apps to whatever desktop machine I am using, usually at work.