I did a quick search here on waygook and havent seen anyone mention lessonwriter.com! I use this website every week and in a few minutes you can create a worksheet that covers spelling, grammar, reading comprehension, etc. The site is free and works like this; Copy a body of text from anywhere (up to 800 words on the free account) and paste it into Lesson Writer and push the create button. (I take a lot of text from howstuffworks.com) The program will automatically pull out a big list of vocabulary words and you can choose what ones you want in your lesson. You can decide whether or not you want a grammar focus, and if you do it will pull out sentences that concentrate on present tense, past tense, present continuous, etc. Then if will display your text in separate paragraphs and you can choose to write a short answer comprehension question, a true or false question, multiple choice, etc. Basically it walks you through each step and asks if you want to include it in your lesson, and at the very end it spits out an awesome looking worksheet that is quite impressive. Try it out!
www.lessonwriter.com