My average day with a Pandora will be as follows:
In the morning, I wake up and unplug the Pandora from the wall charger. (Nightly recharges keep it going through the entire day.) I turn on something similar to Google Reader and read up on the latest news and happenings as the day winds up.
As I ride to work, I might catch up on a podcast or two, depending on the length. Once I'm at work, I'll use it as a free cellphone, either through Gizmo's services or through a standard SIP connection to an Asterik server I'll have set up and plugged into my phone line at home. Once everything is running, I'll turn on my music library (which syncs/streams from a service like MediaMaster or my home computer) and close the lid.
Once at home, I generally use my desktop for e-mail and IM, but there's always the event that I might be out and about. In that case, I'll have the Pandora by my side at all times, fully loaded with PIM software. I might stop by a Starbucks or other T-Mobile Hotspot location to relax. I might pull open a savestate of a game like Wipeout while I wait in long lines. At least three times a week I'll definitely update my calendar with new events, which will automatically sync the next time my Pandora is near a Wifi location.
If I decide to go ahead with my idea, I'll use a Sprint, Verizon, Nextel, or T-Mobile Wireless Broadband USB stick to keep my Pandora online and kicking at all times, effectively turning it into a mobile communication device (IM and cell-phone to name a few).
On some days, I meet up with friends to talk about life, politics, and programming. Since I'll have my Pandora on me, movie+game nights are as simple as a few wires here and there.
Mobile entertainment can come in handy elsewhere, of course, but I find it more useful when I've sat down to spend some quality time enjoying it. It will effectively replace my aging desktop in this aspect more than anything else: gaming will be a breeze and an absolute joy with the Pandora's controls.
Lastly, when I'm relaxing in bed, I might chat, play an Interactive Fiction game, read an electronic book (found a whole collection of really good books in PDF form online), or otherwise generally enjoy the evening.
There are many other odd-ball situations that pop up which can make the Pandora twice as useful. A few simple wants are looking up something real quick, or keeping notes on something, or needing to access my home computer for a file, etc.
In short, it will become part of my daily schedule. There is no other reason why I am so excited about the Pandora.