Possible pitfalls of taking a year off to travel following a PhD instead of immediately starting with a post-doc position?
Although I envy a PhD graduate who has the funds left after obtaining a doctorate to pursue a year of travel, I don't think this is a good idea (unless your degree is in anthropology, in which case it's probably a great idea!) Some thoughts:


You are at a tenuous position in your career -- you've reached a peak (not necessarily the top-most peak), and you are very prepared for academia (although possibly not mentally, as you allude). Your degree has a half-life of sorts -- others will continue to do research in your field while you jet-set the world, and your own work will start to get stale. Now is the best chance you're going to have to convince people who may want to hire you that you're a candidate at the tip of the spear, so to speak.
While a year is not too long, your letter-writers aren't going to have as fresh a picture of you from which to paint their glowing recommendations. You can mitigate this by asking for letters now, but you'll want them to review the letters a year from now (and change the date!) when they do submit them for applications.
Academia can be a fierce environment, as you've probably learned during your candidate years, and possibly why you don't feel you're ready. But, removing yourself from the process for a year doesn't help your case in academia, except to possibly calm your spirits in order to be reinvigorated in a year. Although not universal, the people working the hardest get the best jobs.


All of that said: do what you feel is best for you. If you're not ready for academia, by all means remove yourself from the process for as much time as you need. Better to have a harder time getting a post-doc in a year than to spend a year burning out on something you're not prepared to do.