I keep talking about ADP. (1, 2, 3, 4, 5, 6) but in my defense, they are the largest of the HR outsourcers. CIO Insight has a great article on what they are doing to create a seamless web portal for their multitude of services and systems. I'm not sure if any other traditional outsourcers are anywhere close to the web services ADP is offering. Certainly software vendors like SAP are well ahead, but if you outsource your HR/PR and a self service strategy is central to your service delivery, ADP is a good place to be. Potentially, you could also pruchase web services, but who wants to build this stuff???
This really goes to my previous posts on web services: to some extent, it really does not matter how non-integrated your systems are if you can create an integrated presentation layer for the initial UI.