1. ReadyBoost - if you upgraded to Vista, you can add a USB flashdrive or an SD Card to speed up your computer. Vista will use it for paging which will be 10-30x faster than paging to your hard drive. Lern more from Jim Allchin's blog or read this Q&A post from Tom Archer
2. Windows Live Mail desktop - If you are a Live Mail/Hotmail user this is a must - using this client version is so much faster that using th web interface - think of it as a combination of Outlook and the web Hotmail experience: you sync your mail and have access to it even when you are offline, and you don't have to wait for web pages to load because your mail isd now on your pc. Download it here or read about what's coming in the blog.
3. Free WiFi HotSpots for T-Mobile users. If you are a T-Mobile customer with a data plan, you have access to all the T-Mobile HotSpots for free. Use your phone number (no dashes) as user name and the last four digits of your social security number as password. Very convenient if you don't have a 3G card.
4. Improve Battery Life. Very simple tip - if you don't use IrDA or Bluetooth - turn them off. If you don't need HSDPA speed, turn it off also - EDGE will be OK for most email users.
5. Free International Roaming with Sprint. Most Sprint data plans include free data roaming in Mexico and Canada. Check this page for details or contact Sprint dirtectly,
6. Free gold game, ringtones, and more at www.windowsmobile.com/domore
7. Video Encoder - Microsoft offers the free Windows Movie Maker (included in XP SP2 and Vista) and Windows Media Encoder which you can use to re-size videos to put them in an SD card for viewing in your WIndows Mobile device - You can create movies by editing multiple video files and audio tracks, and save them using your preferred framerates and screen sizes.
8. Virtual Earth Mobile - I have been using Local Live Search in Windows Mobile 6, however I still like Virtual Earth Mobile - it is a small app that works beatifully providing maps, local search and trafic. It has proven extremely useful many times while on the road. Highly recommended (and Free).
9. Custom Screen - This is one of those features in WIndows Mobile that more people should take advantage of : the ability to customize your home screen. There are basic tweaks you can take advantage of, free themes for download and commercial products - here is a good blog post that summarizes what is available
10. Phone as a Modem - If you have a data plan chances are you can use your phone as a modem. Here is post on how to do it with a Dash. AT&T's site has good tutorials for most phones.
Do you have any suggestions for numbers 11 and beyond?