As excitement gears up worldwide for the royal wedding this Friday, we thought we'd take a look at how wedding frenzy for everything from flowers to fruitcake is manifesting itself online. Not only have searchers caught the matrimony bug, but savvy businesses around the world are capitalizing on the increased interest in the day with clever online ad campaigns.

We often tell marketers that “searchers are very engaged;” it now appears that the engaged are very searched. Searches for [royal wedding] have been steadily rising since the engagement announcement and have risen an additional 90% worldwide since the beginning of April as more details of Kate and William’s big day are revealed. Search volumes have boomed—from the [royal wedding carriage] (up 70 percent since it was announced in March), to Kate’s choice of coat at official appearances and the [royal wedding flowers]. Smart merchants have had plenty of opportunity to grow their wedding-related businesses online.

For example, a centerpiece of royal wedding coverage has been Kate’s sapphire engagement ring. Searches for [sapphire rings] are up almost 25 percent in 2011 compared to 2010, and jewelers have taken notice. U.S. retailer HSN saw huge sales of its various sapphire rings and other royal wedding memorabilia, including commemorative royal wedding coins. In fact, HSN had more than 350,000 impressions and over 20,000 clicks since its royal wedding online campaigns began in December 2010. Across the pond, Martine Wester Jewellers in Fulham, London, has seen sales of its £29 replica sapphire engagement ring skyrocket as much as 250 percent.

While many Londoners are leaving town and renting out their houses, scores of people outside the city are trying to get a front-row seat at the festivities: searches for [london vacation] are up more than 10 percent since the beginning of April. Virgin Atlantic Airways used online campaigns to promote its onboard street parties for passengers flying on the day of the royal wedding.

One of the oddest searches that turns out to be royal wedding-related is [fruitcake], which is up about 15 percent in the last 90 days in the U.S. and up 8 percent year over year worldwide. Turns out, fruitcake will be the official royal wedding cake flavor. If you weren’t lucky enough to score an invitation, you can still eat like a wedding guest thanks to clued-in bakeries around the country whose well-timed ads led to soaring fruitcake orders.

So settle in with your sapphire ring and fruitcake and tune in to the Royal Household’s YouTube channel to watch the whole event. And if anybody knows where you can actually buy one of those royal carriages, let us know.