Firefox only: Firefox has long had a handy built in spellchecker, great for proof reading emails, blog posts and other communications. What if you want to use the built-in spellchecker on a static web page however? Use this bookmarklet.
By dragging and dropping the simple bookmarklet below to your bookmark toolbar, you can activate the spellchecker on any static page.
Not only can you see the errors, but because the bookmarklet sets the text content of the page to editable you can actively correctly the mistakes so when you cut and paste the text the errors are fixed. It's a handy way to proof a draft sent to you via email or make some corrections to a text you're copying and pasting.
Have any handy bookmarklets—Firefox-centric or otherwise—to share? Throw them in the comments below.