When I go somewhere my X30H goes with me. PDA phones are interesting as an idea but the one I liked the most (Cingular 3125, the WM5 flip phone) was discontinued. My PDA is my MP3 player, e-book reader, video player, mobile web browser, and even has a copy of the phone numbers that are on my phone. (It just so happens both my non-PDA phone and my Axim sync with Outlook so my phone got appointment data from the calender and the Axim got the address book data from the phone.)
I got myself an extended battery from Osprey-Talon through Amazon and haven't needed to use the original battery since. Since I use the original case, the extended battery's size doesn't cause me any problems. It just makes the Axim harder to get out of the case. (Which would be a good thing if you use the belt clip.)
Amazon.com: 2000mah X1111 Li-Ion Replacement Battery for Dell Axim X3, X3i, X30, X 3, X 30 PDA Models: Electronics
I also got a travel charge/sync kit from Amazon that has a retractable USB sync cable and AC/Car adapters that plug into it. For syncing or on the road charging I use the cable. For charging at home I use the cradle.
I would not recommend the styluses with built-in pen that I got though. The pen caps come off far too easily which can make it hard to get the stylus out of it's holder and the small caps can easily get lost. They're also made of plastic rather then metal. Next stylus I get will be OEM.
I'm also thinking of getting a Think Outside (aka IGo) Stowaway keyboard. Used the Ultra-slim version with my old PDA but would need a bluetooth one for use with the Axim.