Take one online stream of information, preferably with an open API. Add one or more streams of information such as an RSS feed. Mix with a blend of techniques like Ajax. Incubate in alpha or beta, or simply serve directly to the Web. Voila, you've just prepared a mash-up, a hallmark of Web 2.0 applications.

One of the most popular mash-up ingredients is Google Maps, with an entire blog dedicated to its use. From HousingMaps.com's real estate maps to the Beer Hunter's maps of where to get a cold one in Ontario, mash-ups are limited only by imagination.

One such blend, SkiBonk, came when former enterprise systems architect David Schorr and his wife wanted a clearinghouse for ski information. "Mash-ups are setting the stage for where information is no longer tied to a single site, but rather interacts and evolves into something new and more powerful," Schorr says.

When he set out, Schorr found sites with ski-related information, but none that combined all of it into one simple graphical interface. SkiBonk takes the Google Maps interface and overlays slope conditions, trail maps, live Webcams, ski area locations, local weather reports, and information on lodging, gear, and food into one tight package. A skier icon marks slope locations worldwide on the map, and a click brings up that multitude of information in one pop-up. Users can submit additional or edited data. Together, SkiBonk and its sister site, WeatherBonk, pull information from more than 20 sources.

Such targeted applications previously may have been expensive, but the relative ease of mixing open information sources makes mash-ups an interesting proposition for Web developers and businesses alike. Using Google Earth, Volkswagen of America hopes to equip its vehicles with in-dash local search. Salesforce.com's APIs have been used to offer quick click-to-call conferencing with contacts through Skype.

Security is always a concern for any Internet-based application, and most enterprise apps don't have open APIs. Still, businesses are beginning to recognize the possible benefits of mash-ups, and customers may soon come to expect them.