I recently purchased a Samsung Epic 4G on eBay to use as a personal media device. It is not activated on any carrier’s voice or data plan, I use it like an iPod Touch. I was able to get it for a pretty reasonable price because it has a bad ESN, meaning Sprint will no longer activate this phone on their network due to a non-paying user. Verizon also does this, so you can get phones for their network cheaply also.
Its nice to be able to check for new emails at glance, and I also have the Google Voice app installed so I can text from it and listen to voicemails. Keep in mind that this only works when I’m on a wifi network, but for me that is home and work which covers 80% of my day.
I also use Google Listen to download podcasts for listening during my daily commute. Unfortunately there is a bug in the current version which required me to associate my gMail account when previously I had only had it associated with my Google Apps for Domain account.
The GPS is functional, although Google maps downloads data in real time, so you have to download a different map application that is built for offline usage if you want to see maps in your car.
You can install Skype, but unfortunately Skype for Android is not fully implemented due to the fact that it would compete with the carrier’s service, so you can only use to chat and make Skype to Skype calls. I did however get calling functional following a lifehacker article (which I’m unable to find now). It involved getting a SipGate.com number and installing SipDroid and Google Voice Callback apps. However there was about a 2 second audio delay during one test call, and less delay, but much more static on a second text call. My cell phone contract expires in 6 months, so I’ll probably re-evaluate a calling solution then.