Even those of us who write professionally for a living often make typos, such as letter transpositions (did you spot "prefect" in the title instead of "perfect", and sometimes our grammar is less than perfect. All of us can use a little help. I've always recommended that my students use spell and grammar checkers built into software like Microsoft Word. However, as we increasingly create documents in the cloud, in browser-based software, that option is not available - enter Grammarly. If you're a regular reader of this blog you know that I don't often promote products, but I'm impressed with this. Grammarly once installed as a browser extension sits in the background watching every word you type. It then underlines words that may be misspelled or easily confused with similar words, either by spelling or meaning. Hovering the cursor over the word brings up suggestions that you can accept or reject. Grammarly also has OS X and Windows apps and an MS Office plug-in (Win only). Highly recommended.
from The Universal Machine http://universal-machine.blogspot.com/