On Wednesday, interactive advertising agency aQuantive (NASDAQ:AQNT) closed out a stellar 2005 with a solid fourth-quarter showing. December-quarter earnings per diluted share rose 50% to $0.15, with revenues clocking in 44% higher at $87.5 million. The company topped market expectations on both fronts.

As the product of the merger between Avenue A and SBI.Razorfish, aQuantive has become a fast-growing, one-stop-shopping hub for online advertising. It will coordinate a client's contextual marketing campaign through Google (NASDAQ:GOOG), but also develop sticky websites for its customers. To that end, its projects include a social networking site for Carnival Cruise Lines (NYSE:CCL) and a multimedia site for Kodak (NYSE:EK) to educate consumers on the merits of digital photography.

Not all of aQuantive's growth has been organic -- it's also been scooping up niche operators in this highly fragmented sector. But this is a win-win situation, since it ultimately gives aQuantive more leverage and broader coverage and recognition.

For 2006, the company expects earnings before stock-based compensation expenses to come in between $0.57 and $0.61 per share. Revenues will grow by at least 22%, in a range between $375 million and $395 million.

That may come as a disappointment to those who were starting to get used to company's heady growth through 2005, but it's exactly in line with analysts' prior hopes.

The advertiser migration to the online realm will surely continue. According to PricewaterhouseCoopers, online advertising is now a $12 billion-a-year business. You see it in the fat income statements being produced by companies like Google and Yahoo! (NASDAQ:YHOO), but you also see it here.

aQuantive has positioned itself as a credible candidate to guide many of those old-economy companies into the new-economy world of marketing opportunities. And unlike Google, at least aQuantive will give you a clue about its projections for future results. Some investors may flinch at paying more than 40 times forward earnings for aQuantive (especially with the top line expected to grow no more than 28%), but the company deserves the market premium.

It was at the right place at the right time, and it's been smart enough to stay right there.

Longtime Fool contributor Rick Munarriz believes in interactive advertising, but he does not own shares in any of the companies mentioned in this story. The Fool has a disclosure policy. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.