tkSpeller

tkSpeller is a tiny utility that sits in the corner of your screen and does nothing until you activate it. If tkSpeller is raised (selected, clicked, 'Alt-Tab'-ed into) while your clipboard contains an alpha string under 20 characters in length (a word), that string will be spell-checked. If it is misspelled, suggestions appear in the tkSpeller window. If you click one of the suggestions, that word replaces what you had in your clipboard.