There is a company named Aadcom that is apparently using some pretty sleazy advertising techniques. Their web site is a little vague on this, but it seems they use what can only be a BHO, a Browser Helper Object, to log the keystrokes of the user when the user is at a web site filling out forms (how is that not illegal?). Whether this BHO sends data back to the company is unclear at present, though I think it is likely.
Afterward, this BHO interacts produces a popunder ad while you are browsing. It is similar to Top Text and Ezula in that the web site connected to in the popunder just might be a competitor of the site you were viewing when the popunder was created.
At this time, there is not enough information about this to give a specific warning. From the description on Aadcom's web site (see below), it would almost have to be that they are using a BHO as part of their strategy. Presently I have no information about how this BHO would be installed. Almost certainly it will follow the pattern of other spyware applications by being bundled along with a host application.
It's possible that whichever BHO it utilizes is one that is already known, in which case it is likely already a target of AdAware. In case it is not yet something that is targeted by AdAware, I recommend checking your system with BHO Demon for unauthorized BHOs. Even without this potential new threat, I'd recommend having this product installed, as it is a very useful tool.
The company has on their web site a fairly detailed description of how they operate. There is an ActiveX control on each and every page, so I'll spare you that danger by quoting it below. The entire description can be found here.

