We are currently monitoring many hosts infected with the spyware called MapKon. As soon as installed the software frequently issues WHOIS requests for all kinds of domains. This way the malware author can register so called typo-domains or domains which recently became available due to errors or missed payment. Once such a domain is registered it is used for further distribution of the spyware.
Currently the spyware is available at www.archivierungsprogramme.com and installs itself invisible with the archieve software like winace. If you read the user agreements carefully you will notice a few sentences stating that you agree in sharing bandwith and the installation of a browser helper object. This browser helper object is responsible for the WHOIS requests, which are made whenever the browser is running.