ValueClick announced today that it has completed the integration of its vcmedia and Fastclick online advertising networks, creating a network with 59% reach among UK internet users.

The announcement, which follows the purchase of the US network Fastclick a year ago, is significant because it demonstrates the increasing competition in the ad networks space and the importance of reach as a selling point for the major players.

In terms of ad network reach, according to comScore data, the re-launched vcmedia network is now second only to in the UK but ahead of players including 24/7 Real Media and Burst Media.

A lot has been happening in this space since we published our Ad Networks Buyer’s Guide last year, including the arrival of the US player BlueLithium on this side of the Altantic.

New arrivals in the marketplace and developments such as the growth of vcmedia  represent a challenge to other key market players (including the likes of Ad Pepper, AdLink, Migration Marketing, Accelerator and AdLink).

More consolidation in this marketplace seems inevitable as reach has emerged as such a key differentiator (although it should be noted that a lack of consistent data to measure and compare reach precisely is a problem for advertisers).

But while reach is important, it is by no means the only differentiator for advertisers to keep in mind.

Buyers have to consider, for example, whether their priority is to reach as many people as possible (often via ‘blind’ networks) or whether they want their brands to be advertised only on a well-defined range of bigger, well-known websites in keeping with the image they want to project.

Behavioural targeting capability is also important with success in this area often dependent on the right technology as well as high volumes of traffic to ensure that ads reach sufficient numbers of the correct target groups and demographics.

Another differentiator is whether the network can add value by offering services in complementary areas such as affiliate marketing and search engine marketing, with a technology platform enabling consistent tracking across different online channels.

Finally, advertisers need to find the best pricing model. ValueClick said today that they have launched a new vcmedia pricing model called eCPM (Effective Cost per Thousand Impressions).

The company said: “It works by translating every pricing model, CPC (Cost per Click), CPA (Cost per Acquisition) and CPM (Cost per Thousand) into an eCPM, giving website publishers access to a larger variety of campaigns, regardless of the original pricing metric. Advertisers in turn will see their campaigns opened up to more publishers, providing them with more variety and reach.”

More about pricing models and other aspects of ad networks in our soon-to-be-published 2006 Ad Networks Buyer’s Guide. We are getting lots of requests for a new version of this report because of the paucity of information in this rapidly emerging area.

We plan to release the updated version of this guide in the next few weeks.