Scythe introduced the Kama Bay Speaker ACE, a new mountable speaker that slides into one of your case's 5.25" drive bays. Most people will probably stick to normal speakers or headphones, but this solution comes in handy in when space is an issue.
The Kama Bay Speaker ACE features four 1.25" concave shape speaker with a real output of 2x 1.5W. You can get it in a black or silver version for $35 (17.95EUR excl. VAT).