ESL: Business English

http://www.english-grammar-lessons.com/irregularverbs/menu.php
English International Lyon

Basically a grammar site, but an interesting format. It's basically drag and place in the correct categories, but there are a lot of grammar skills, from present simple and irregular and passive to conditionals. This type of website will appeal to those students who prefer text-based programs. There is no audio, but the lessons are short, with a check button at the bottom. There is a 'Hangman' game http://www.english-grammar-lessons.com/eglhangman.html that works on using irregular verbs.