From the reviews it seems as though this is a very basic, but mostly handy app to have for $1.50

http://www.amazon.com/gp/product/B004UWTLZE/ref=as_li_ss_tl?ie=UTF8&tag=apps-aholic-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B004UWTLZE#productPromotions

There may be better apps, but this is pretty cheap.  (android only)