Making services consumable in the browser. Increasingly, the common web browser is the place where meaningful service integration is taking place. Because of this, building services that aren't easily consumable in the browser can be a death knell for the service, because it puts its consumers in the business of building and maintaining adapters or using a Javascript SOAP stack (if you can find one) before the service can be used and measurable work accomplished.
Considering syndication over "service-izing." The browser is an important consumption point, but so too are the growing syndication ecosystems, of which the blogosphere is the largest example. Not every SOA service can or should be converted to a syndication model, but if you aren't considering this option with each service you create, you should be; there are tens of millions of RSS feeds available today, starting from zero in the beginning of 2003.
Deeply embracing URI addressability. Of all the things in this list, this might be the most important one. The hyperlink is the fundamental unit of thought on the web, and it should be in your service designs and (hopefully granular) schemas as well. Giving each discrete piece of information, every service, and all content a globally addressable URI instantly gives a service, and the data it carries back and forth across its interface, access to countless new consumption and reuse scenarios.
Using Ajax as the face of your SOA. This point emphasizes yet more service consumption in the browser. Why? Because the browser model, with our newest high-speed corporate networks, fast desktops, and latest browsers, has finally becoming a very capable way of distributing software and associated updates.
