Request a Quote form module for Joomla is the one and only form module, which has been developed keeping the business in mind. It's the best-fit module for corporate websites, service websites, eCommerce websites, etc.
RSS Ticker is a great Joomla ticker module, which works best for news websites, magazine websites, etc.
Show-off Slideshow is a nice and light weight Image slideshow module, where you can define the images, captions and url for the image slides. It looks good on well-designed websites.
Sleek Twitter is an ultimate and light weight Twitter Display module. It can list latest tweets from a user. All you have to do is, set the twitter username in the parameters screen and you are done.