Across Lifehacker's of recent roundups of laptop chill mats, the Logitech N100 was a good all-round performer. A current deal at Officeworks selling it for $29.95 makes it even more appealing.
The N100 falls squarely into the middle of the chill mat market: it does have a fan, but it doesn't have speakers. For many people, that's an entirely acceptable combination, and some form of cooling is definitely a good idea to protect your legs and keep your laptop running smoothly. (The discount price doesn't appear to apply at Officeworks online, though at $39.25 it's still cheaper than list price.)
Commenters at OzBargain have also noted that this deal may qualify for an additional cashback offer from Logitech. That's a good way of saving even more money, though as ever you need to be thorough to ensure cashback deals pay off.