In that vein I wholeheartedly recommend Shortyz crosswords.
What's so great about a crossword app?
Well there are a few things that really stand out for me.
First is that I can choose to reveal any letter in the crossword at any time by hitting the menu button on my phone. I'm no crossword genius so being able to reveal a letter or two of a word allows me to actually learn while playing rather than just getting frustrated and giving up.
Secondly is that the app is set to automatically download daily crosswords from around the net when I log in.
Always fresh!
Finally its just how easy it is to navigate around the crosswords. It intelligently allows you to pinch and zoom snapping the crossword to various sizes. You can also rotate your device to landscape mode if you want a bigger view.
If you're going to have one crossword app on your phone or tablet this is the one to get. Oh yeah its free!