Lijit Networks, a provider of custom site search and advertising solutions for online publishers, has secured $10 million in financing in a round led by new investor Highway 12 Ventures. Existing backers like Foundry Group, Boulder Ventures and Colorado Fund I, managed by High Country Venture, also participated.

Lijit says transactions on its advertising services platform have grown 74 percent since Q4 2010 and that its online publisher network has grown to include more than 17,000 websites, 1.5 billion pageviews a month, and over 106 million unique visitors per month.

Lijit Networks was founded in June 2006 and has raised $28.3 million to date.

But Lijit is really an advertising network. Publishers that use Lijit also get access to lots of stats about what’s going on with site searches. And they have an option to join the Lijit ad network to put display ads up on their sites – not just on search results – targeted via that data. So far, so good. Lijit doesn’t take inventory unless they can get the publisher a minimum $1 CPM, and 30% of their 700 million page views on publisher sites serve Lijit ads. They say that will grow to 1 billion page views by end of September this year.

Gross revenue, mostly from those display ads, is on target to hit $4 million – $5 million this year, CEO Todd Vernon told me earlier today. And most of their display ad publishers have joined Lijit in the last 90 days. Last year, revenue was near $0.

Vernon says that the company is able to get premium advertising rates for publishers by combining that search intent data with demographic and content targeting, and that they work very well with mid and long tail publishers who aren’t yet big enough to hire their own sales force.

All that growth and potential means Ligit gets a new round of funding. Existing investors Foundry Group, Boulder Ventures and High Country Venture have put another $6 million into the company, bringing the total to $18.3 million to date.

If revenue trajectories continue the company will get to profitability by the time they’ve spent this round, says Vernon.

Lijit, the search widget that offers bloggers a simple solution to index all of their content, has been slow for the last few months: Really. Freakin. Slow. Search results have been taking 20 seconds or more to load (though it’s unlikely that many people stuck around to see them), rendering the service useless.

Thankfully, Lijit has been on the ball, and has recently spent over $500,000 to increase their server capacity. Lijit CEO Todd Vernon says that the site was having a hard time coping with rapid growth since January, and that the slow speeds and sporatic downtime in April and May occurred during their move from independent server boxes to a dedicated server farm. Now, he says, the site has at least five times as much server capacity, with room to grow. Let’s hope that’s enough – bloggers aren’t going to put up with something that bogs down their site and drives away traffic.

In May the site also managed to snag a deal with b5media, a blogging network with 350 properties. Lijit lets users simultaneous search through content on a particular blog and on related sites, which appeals to b5media because it increases traffic between their own blogs. Vernon says that the initial response has been very positive, with a pageview increase of 1.5% across the network directly attributed to the widget.

The round was led by Boulder Ventures and joined by existing investors Colorado Fund I (High Country Venture) and Brad Feld. The round brings total funding for Lijit to $4.2million.

Lijit’s search service allows readers to search blog publishers’ posts, bookmarks, blogroll, and more from a widget placed on the publisher’s property; essentially a one point box to search any published material from a company or individual no matter where it is, be it on blogs, Flickr or other social networking sites.

Lijit’s search statistics can be utilized by publishers to better understand what users search for on a particular site when they visit.

Peter Roshko, General Partner at Boulder Ventures will join Lijit’s Board of Directors as part of the deal.