Big thanks to Rolf who sent me the link to this website. I'm a big fan of tools that don't require registration and are free and easy to use. Textivate ticks all the boxes. It allows you to automatically generate a range of interactive browser-based activities based on any text of up to 500 words. Simply type or paste a text into the box and click 'textivate now' button to see the available exercises (gapfills / sentence arrange / paragraph arrange / punctuation / splitting words). Great for exam classes or any other reading-based lessons.