I'm surprised by their extensive list of customers, and also the fact that customers seem to be happy to be identified as their customers ... http://www.demandbase.com/who-uses-demandbase/customer-list/

Hardware manufacturers & telecomms seem to feature heavily:

(a selection) ... Adobe, Dell, IBM, AMD, Box.net, Cisco, CSC, Comcast, Freescale, HP, Lenovo, Motorola, Novell, Qwest, Salesforce.com, Siemens, Symantec, Verisign, VMWare, Vodafone.

And there's several anti-virus/anti-malware companies listed there.

UPDATE: The LeadLander.com site also lists their customers - Microsoft, Motorola, Red Hat and Cisco, among others.