After twenty years of enslavement to Microsoft's software, I swore I would never let another company gain too much of my loyalty. But Google is making it damn hard, turning out product after product that I find makes my computer life easier. Those I use daily include:
Google Reader: For gathering RSS feeds (the sometimes-truncated posts from the many blogs I follow so I don't have to visit each one individually) this reader is the most convenient I've found. It allows me to tag, forward, and group interesting content in a logical, pleasing layout.
Google News Alerts: This service allows me to create search terms (Tom Barlow, for example). Each day (or more often if I choose) it searches the internet for new content in which my name appears, and sends links to each in a consolidated email. Very handy for tracking hot topics.
Google Notebook: When researching topics for posts, I often visit a number of internet sites. Notebook allows me to clip out relevant text/pictures from those sites and compile them in my notebook tagged with the address from which the info came. This makes assembling the final story with proper attribution a snap.
Google Maps: In the novel I'm currently working on, the heroes ride a motorcycle from Seattle to Ohio. I was able to create the route on a Google Map and keep track of time and distance. Using the Google Earth feature, I was also able to virtually drive the route to see what my characters would have seen.