A lot of forums and boards provide very small textareas for new postings. If you type a longer posting, you have to scroll up and down, to read what you have written and to proceed. This situation is annoying.
The Resizable Textarea extension for Firefox, once installed, lets you drag the right/ bottom outer edges of many textareas to resize them dynamically. This might come in handy e.g. when the comments box in a blog is too small.
Firefox, Browser, Resizable Textarea, Extension, Addon, Add-on