The HP Jornada PDA is the best unit on the market right now. Everyone knows and uses "Palm" like "Coke" or "Liquid Paper" brand names, but in my opinion Palm isn't the best out there.
WIth the HP you can set up a direct link to your home computer (with the correct software) and upload your log to your home for safe keeping. In other words, while your on a trip you can log your time, hook up to the wireless internet and send your information to your pc. An easier way would be to set yourself up an ftp address direct to your computer at home for the flight log program your using.
The color, wireless, with a modem PDA is going to run in the $500-$700 range. It would allow you to access the internet for weather checks, check your email, or checkout what's happening on flightinfo.com.
Give it a year or two and the prices will be in the $350-$600 range. Wireless connect charges are around $20-$30 a month for unlimited use if you look hard enough.