Microsoft may be the only company with the wherewithal to challenge Google’s Internet search dominance head on, but a number of firms are trying to outflank Google with services that handle aspects of search not covered by Google’s index of Web pages.

Aardvark - a firm whose cofounders include two ex-Googlers - is pushing something it calls “social search.”

Instead of looking at Web pages to find answers to search queries, Aardvark’s service taps a person’s network of social contacts. Ask Aardvark for anything from restaurant recommendations to home improvement tips, and the service will relay the question to Facebook and Twitter friends who have identified themselves as “experts” on various topics.

The service, which has earned praise from the New York Times’ David Pogue and other tech bloggers, was launched as a beta version earlier this year but accessing Aardvark required using instant messaging software or an iPhone app.

On Wednesday, the company put the search box directly on a website - vark.com - making its social search service more accessible to a larger pool of people.

Like the so-called real time search engines popularized by Twitter, Collecta and OneRiot, Aardvark represents a still small, but potentially dangerous trend for Google: Much of the content that flows through these new types of search services is not necessarily accessible by Google’s search engine.

Google is trying to address the situation by reportedly licensing the Twitter data feed. As more newfangled forms of search emerge, Google may find itself having more such talks.