Typically, external HDD enclosures for 3.5-inch HDDs are thin and made to be passively cooled. A few of them have tiny fans to keep the drive inside cool. A new offering from Thermaltake has surfaced called the Max 5G that has dual 80mm fans to keep your drive running cool and the enclosure looks really sweet too.
The Max 5G has blue LEDs behind the fans and those fans only spin at 800rpm to keep the HDD cool, but not make too much noise. Those blue LEDs can be turned off using a switch on the back of the enclosure. The device is designed to stand upright and a swiveling stand on the bottom keeps the enclosure from falling over.
The Max 5G connects to your PC via USB 3.0 and has the power supply you need to keep things juiced up. It will fit any 3.5″ SATA I or II HDD or SSD. Thermaltake is mum on pricing and availability at this time.