Social Engineering
As much as you may hate to admit it, you may not be able to solve your wireless problems by yourself. Since the heart of the problem is caused by lack of coordination (and communication) among users trying to run a number of wireless LANs in too small an area, the most effective solution would be to apply the design techniques used in large multi-AP WLANs.
You may be surprised at the willingness of people to work together to solve a common problem - especially if they don't really have to do much. Put up a sign and call a meeting of your apartment building, dorm, or neighborhood. If you've got the a WLAN problem, chances are others do too.
Once you've got the interested parties together, the main order of business is to see if you can work out a satisfactory channel assignment scheme. If there are only three APs involved, the job is pretty simple. But if you're dealing with more APs, you'll have to put in a more effort.
Make a diagram of the APs as close to scale as you can get it. Once you have the APs located, it's just a matter of juggling channel assignments so that APs using the same channels have the lowest signal strength with respect to each other. Since signal strength is primarily related to distance, a practical approximation of this rule is to locate same-channel APs as far apart as possible. In some cases, building construction and other RF-unfriendly obstacles like trees, water, screens, etc. may allow you to bend this "farthest-distance" rule a bit. In multi-story situations, be sure to think in three dimensions because radio waves travel in all directions!
Once you have your channels assigned, but sure to assign unique SSIDs to each AP. Though you want to treat the APs as one big WLAN from a channel assignment point of view, you still want multiple, separate WLANs from an operational point of view. Unique SSIDs will keep clients from trying to roam where they're unwanted.
Finally, if you find that your neighbors are unfamiliar with the wonders of WEP / WPA, MAC address association control (filtering) and other WLAN security features, help them get that set up too. With the problem of WEP-related throughput essentially gone from current-generation WLAN equipment, there's no reason to run wide-open WLANs if you don't want to.