1. As everyone else has said... Missing Sync is a MUST HAVE for any Mac user who has a WinMo phone
2. Livemesh mobile... If you're not using Live mesh yet, you need to start using it now! It's AWESOME!
3. If you use Google calendar, try NUEVASYNC (nuevasync.com). It's a free webservice that allows you to use Activesync (on the FUZE) to automatically sync Appointments and Contacts to your google calendar/contacts wirelessly (exchange for all of us). Unlike Oggsync, you don't need to install anything on your phone.
4. Coreplayer... This will enable your FUZE to play almost ANY Video format you throw at it! It will eat anything for lunch. Just transfer the video over to the FUZE and use Coreplayer to play it. Done. No transcoding, no resizing... just done.
5. iGO 8, Tom Tom 7, Garmin XT, or any other GPS app... I really want to see how you feel about your phone being a Turn-by-turn GPS instead of being stuck with Google Maps.
6. WinMobile Torrent... Torrent client on your phone. Enough Said.
7. Kinoma Play... The only thing keeping me from replacing Coreplayer with Kinoma Play is the fact that Kinoma won't play AVIs. KP's UI is AWESOME and the ability for KP to be your ORB client is almost worth the $30
8. USE MICROSOFT VOICE COMMAND!
9. The Sprint Touch Pro comes with Sprint TV, if you want a taste of live TV on your phone, use MobiTV.
10. MusicID is pretty cool... but most of the top-shelf smartphones have a "listen to ID your Music" program
11. Use the built-in RSS hub to automatically download Feeds and Podcasts
12. Skyfire, while a little bit of a "jerky" experience compared to Opera mobile 9.5, is a must-have when you just NEED to view flash sites. The newest version works on VGA devices. It's also the fastest mobile browser that exists right now.
13. Klaxon (I like to call it the Louise Woodward Alarm) is awesome.
14. If you're not using a stereo Bluetooth headset, then try out a Program like BT Toggle or BT Audio so that you can listen to anything using any bluetooth headset.
15. AE Button Plus... it allows you to control which buttons do what on your device... almost any button and button combination you can think of... no holds barred! With it, I've configured my Diamond's WiFi to toggle with a long keypress of the "enter" button on the D-pad and my A2DP stereo Bluetooth to toggle with a double press of my "end" key. I've set up my Girlfriend's Touch Pro's enter key to act like an "ok" button when double pressed (very handy!).
16. Thumbcal ... a much nicer calendar
17. Resco Explorer is a must-have!
18. 1-calc is a good calculator program to try out
19. Gyrator 2 is a tricky program to configure but will allow g-sensor rotation in any program you want.
20. TaskFacade is a nice Task switcher... make sure you close it out before playing videos in Coreplayer or Kinoma Play or else it'll slow everything down.
21. G-Light gives you total control of the Light sensor and backlight including program-specific backlight levels. My Girlfriend loves the fact that her screen will now totally dim when she wants to read an ebook.
22. While Windows only, Gremote is just AWESOME. It turns the phone into a universal Remote control, trackpad, airmouse, keyboard, and game pad for your PC (via Bluetooth or WiFi)!
23. Another Windows only must have is either SOTI's pocket controller. This allows total control of your phone via 3G, WiFi, USB, or BT connection.
Check out the forums at Xda-developers.com for a TON of cool stuff you can do with the FUZE (Raphael and Touch Diamond Forums specifically).
Someone on PPCgeeks.com also made a program that plays a custom sound when you flip out the keyboard... everyone I know with a Touch Pro downloaded it and set it to play the Transformers transforming sound! AWESOME!
PS - I must've edited this post 6 times because I kept forgetting some of these programs!