Windows Live! Lives...
Microsoft is massively increasing its offerings under the Windows Live platform umbrella and it's worth a look if you're doing anything in the web space (who isn't these days).
From its initial configuration of Messenger, Mail and ID management, Microsoft has (or is adding) support for capabilities as diverse as Agents, Alerts, Contacts, Drives, Galleries, Search, Shopping, Spaces and so on. It's astounding how aggressively Microsoft is moving into creating web services that 3rd parties can take advantage of when development their applications.
The most often seen example on the Internet today is arguably the inclusion of Google Maps or Windows Live Maps in a website. Instead of implementing mapping functionality, turn it over to Google or Microsoft via a specially crafted URL that returns back the needed information. Where in the "old days" this would have been attempted with binary components such as ActiveX or byte-code components such as Java applets, the web is increasingly moving to more dynamic contact such as AJAX to support these features. This makes it more browser-agnostic and easier to deploy in corporate intranets where there can be vigorous security systems in place.
As an example, one of the interesting ways to include Windows Live in your site is to make us of Windows Live ID to manage authentication of your users. This requires the end-users to have (or create) a Windows Live ID to work, but it makes it possibly to implement seamless logins without creating a lot of authentication, user account management services on the back end. Microsoft has even created a helpful SDK that provides samples and illustrations on integrating Windows Live ID into a site.
Live Search is also another area that is going to be very useful to sites that need a Search capability but don't have the time or resources to create a search database of their site (or buy an appliance such as those from Google that will do this automatically). Instead, the developer embeds some HTML and Jscript into the page to access Live Search and Microsoft takes it from there. They limit this to 10,000 hits/day and so it isn't going to spawn some Google look-a-likes out there, but it is useful to many medium-size corporate web sites that won't have huge numbers of search hits.
I highly recommend taking a stroll through the large and growing collection of services from Microsoft Windows Live. You can find more here.