All images are clickable. But the easiest way is to click on the first one and scroll all with the arrow to the right 🙂
1998. Google Beta version
1999. Google is already working.
2000. Advanced Search and Adwords
2001. Appeared Google Groups
2002. Tabs and Google News
2003. Minor restyling
2004. There are no more tabs. Already closer to the modern mind?
2006. Google services are expanding: maps, video, personalized search
2007. An increasingly ascetic design
2008. Services carried in the top panel
2009. Search settings moved up
2010. More salary for designers!
2011. Black heading pleases
2012. Google+ came
Pictures are taken from the Slideshare presentation.