I personally have found some very usefull tools of google's Blogger service that would make documenting a roadtrip very easy from a mobile phone. For example, they offer audioblogs (where you call your blog from your phone and leave an audio entry), as well as email blogs (where you can email pictures and text from your phone to a specific email address).

Personally, I think it makes it really easy to do some neat stuff, and it's easy to use. And the cost is zilch, unless you do what I do and host the blog yourself.

That's just how I would document a roadtrip in additon to the usual video, photos, and of course, the ol' noggin.

-Brad