I've just come across 'Wordle', a nifty tool for generating 'word clouds' from the text that you provide. Creating your own cloud is easy, quick and you can tweak how it looks by changing the colour scheme, font and layout.
The advantage of using this website is that teachers and students can create a wordbank together and the finished article can either be printed out or displayed on an interactive whiteboard by clicking the 'Open in Window' button. Alternatively it is simple enough for students to be able to create their own 'Wordles' if you want them to use the website on individual workstations.
Ideas that sprang to my mind as being ideal 'Wordles' are wordbanks such as finding alternatives to 'said', 'went', 'good' and 'nice' but the possibilities are endless. Topic related wordbanks make excellent 'Wordles' too.
I think this website has good potential for encouraging children to improve their word choices in written work.