There are a ton of apps that make this PPC really sing. Some expensive, some cheap some free.
The first one I would recommend is: SPB It's a new Today screen that puts your access to all programs into tabs and have picons on the screen to launch the apps. This is well worth it for the convenience of accessing different programs. It makes the screen just like a windows or MAC desktop. It facilitates organization of hundreds of programs for easy access.
The second MOST important app you should get is Sprite Backup. I've tried several and like Sprite. Set it to auto backup your system each day and save the past 5 days on your SD card and some day when your PPC won't boot right, a few minutes to restore will save you lots of time reloading everything.
Beyond that it is whatever you want to do. The phone has ample memory to run many many programs as long as you store the programs on your SD card. Some may require they be stored on the phone memory for speed but usually the application will advise you what is required here. Stuff close to the processor needs to be on the phone, stuff that is not such as a game can usually be stored on the card.
I will say, the 6800 is one of the best time savers I own. But I have it loaded with lots of stuff.
TomTom for GPS
Opera for a better internet browser
PDANet which allows me to tether the 6800 to desktop and laptop PC's
sling media to watch all my dishnetwork channels anywhere.
SPB weather
stock quotes to track my portfolio
Some free apps like adobe reader for pdf files
Flash plugin is a memory hog but if you need it...
If you travel, you may wish to get Verizon with EVDO Rev A data as this is much faster for the streaming video stuff and has a large footprint across the nation. If your service is adequate, and less expensive than Verizon, the you should do fine. Just know that there are other services with varying performance that greatly affect some of the apps on the phone.
Re: Skype- Try
this
or,
this
For sources of many fine apps- try
www.handango.com