For all the companies operating in the social media marketplace, there are really only five options for companies looking to establish a strong presence: blogs (WordPress), Facebook, Twitter, LinkedIn and YouTube.

This is where the biggest “parties” are happening so it makes complete sense to focus your efforts on them. The “Big Five” sport the biggest audiences and, in theory, offer the biggest bang for the buck.

Their emergence as the dominant players reflects the natural evolution of any market in which there is a small group of large companies and a large pack of smaller companies with lots of aspiration but little market share.

One of the key questions, however, is whether there’s any value for companies to consider activity beyond the “Big Five”? Does it make sense to explore the use of MySpace, Foursquare, Flickr, Tumblr, Friendster or Orkut? And what about Gowalla, Posterous, Digg, del.icio.us and StumbleUpon?

While it is easy to just focus on the “Big Five”, there are plenty of interesting opportunities to leverage other social media services to serve different interests, audiences and geographies.

For example, MySpace, still had 64 million unique U.S. visitors last month, and has maintained its status as the social network for musicians and music fans. The company recently unveiled a new, cleaner home page that looks a lot like Facebook’s.

For companies looking to attract audiences in Brazil and Asia, Friendster is worth considering, while Google’s Orkut is a strong presence in India and Brazil.

Flickr doesn’t get much attention these days as Yahoo struggles to find its way but it had 23 million unique U.S. visitors last month. Tumblr is gaining a lot of traction as a user-friendly alternative to WordPress, while Digg is showing signs of life after badly sagging.

And then there’s new, emerging markets such as location-based services in which Foursquare and Gowalla are battling to establish strong footholds. Although still unproven, companies such as Ann Taylor and Starbucks are experimenting to see whether they have potential as new social media channels.

The challenge for many companies is trying to sift their way through the multitude of social media choices. In many cases, it is easier to simply stick to the “Big Five” because there’s less risk or guessing involved. It’s like the old adage that “nobody ever got fired for buying IBM”.

That said, there are alternatives definitely worth exploring to take advantage of niche, emerging and geographic opportunities.

For some companies, using social media services off the beaten track could be a way to differentiate themselves in a marketplace in which everyone is using many of the same tools.