As already stated i'm Google addicted (too much).
- GMail is wonderful as i never loose any eMail (which i frequently did when i used e.g. GMX & a local eMail client).
- GCalendar is so well designed that i simply love it.
- GoogleReader is a pretty fine RSS reader.
- Picassa is the best free photo organizing software i know about (picasa web albums cannot reach flickr i have to admit).
- Blogger is what you're currently reading.
Today i have to praise GCalendar even more! RememberTheMilk and WeatherUnderground integrate tightly into it via iCal feeds which makes it even more usefull!

Play around and enjoy the fun!