Attu is the furthest West that you can go in the Aleutians before you find yourself in Russia...
Attu was one of the 2 Aleutian Islands invaded by the Japanese in World War II, and was the only island where US Forces engaged the Japanese in combat when they re-captured the island in 1943. Attu Island is therefore the site of the only instance of military action against Japan in the USA. (A good Trivial Pursuit question there...).
Today, the only inhabitants of Attu are a small crew of US Coast Guard personnel manning a LORAN station. The LORAN system is on borrowed time, since it has largely been superseded by GPS. It is likely that in the next few years Attu will cease to have any human residents.
The Japanese also invaded the island of Kiska, but withdrew without detection from that island several weeks before the US landed on the island in August 1943. The re-capture of Kiska was notable for a number of tragic "friendly fire" incidents, as combat forces confused by poor weather conditions started shooting at each other. Other casualties also resulted due to booby-traps laid by the Japanese, and there were a number of other fatalities caused by the extreme conditions. The final total of fatalities was close to 200 - a rather embarrassing outcome from invading an unoccupied island.
Here is a sailing blog containing many pictures of Attu and Kiska.
And here is a beautiful picture of the Aleutians from a bird-watching tour boat.
Apart from occasional parties of war veterans from both Japan and the USA, the main visitors to Attu since the end of World War II have been bird-watchers. The position of Attu, located between East Asia and the Americas, results in numerous birds being blown to the island, where they fly around as strangers before finding their way elsewhere.
For many years a company named Attours operated birdwatching expeditions to Attu. Here is a web site that includes this report of a bird-watcher's visit to Attu. Attours took over the abandoned Loran-A station formerly managed by the U.S. Coast Guard, and ran trips every Summer to the island. Accomodations were rudimentary, but the visitors ate like kings, thanks partly to the provision of fine food by a gourmet chef. Sadly, the Attours trips ended in 2000 when the infrastructure became too worn out to support any more visits. This is an account of the last trip to Attu in the Fall of 2000.
The climate in Attu is very hard on any man-made item - a constant diet of wind, rain and moisture eventually wears out most building and fitting components. Here is another more detailed account of a birdwatching trip to Attu.
Now the only visitors to Attu are occasional Alaskan cruise ships that drop anchor for a few hours at a time, and the odd yacht that anchors for a day or two in Casco Cove. And...the interestng birds.