Overheating fish tank

My parents decided to hold a garage sale about a week ago.  While searching for stuff I wanted to keep, I came across a 5-gal aquarium.  Over the weekend, I setup the tank, got a couple of guppies, and now enjoy a bubbling fish oasis in my living room.

For the most part, everything worked out great, except for one small problem.  The tank lid has an incandescence lamp for providing light, but it also heats the water.  Because it's such a small tank, the temperature continually rises, making it so I can only have the lamp on for about 2-3 hours before the water gets above 85F.  After searching the local pet stores for an LED aquarium lamp and failing to find one, I decided to improvise a little.

Left: new LED bulb, Right: old lamp bulb

Searching Home Depot, I happen to come across a Philips 3 watt LED bulb for about $15.  LED bulbs are still pretty expensive, but I took a chance on it, thinking if it didn't work, I'd find a different use for it.

One little, two little, three little fishies...

So far, so good.  The LED bulb is just a bright, and seems to make the water a little less yellowish. Current temperature is hanging around 78F.  I'm going to leave it on overnight and see if there is any temperature fluctuation.  While this wasn't a huge project, it reminded me that even if the specialty stores don't have what you're looking for, you can always find something that will work somewhere else.