Plastic Jungle, a Mountain View, Calif.-based company that runs a gift card exchange, says it has raised $7.4 million in a round led by Redpoint Ventures with participation from previous investors Shasta Ventures, First Round Capital and Bay Partners. The company raised $6 million in 2009.

Plastic Jungle is one of the many companies trying to solve the problems around the gift card economy, as I highlighted in my post about CardPool, a San Francisco-based, very early-stage startup. According to some estimates, nearly $5 billion worth of cards go unclaimed every year. It allows consumers to get cash for unwanted gift cards for up to 92 percent of the unused balance and buy gift cards at up to a 30 percent discount.

In the 2009-2010 holiday season, Plastic Jungle saw 450 percent year-over-year revenue growth. The company gets 118,000 monthly visitors to its web site and is growing at about 60 percent per month.