There are actually about 12 different formats included in the "pdb" container that I know of from the top of my head. Best about those formats: they are (mostly) not compatible. So you need a few software readers if you want to be able to read every single one (to name put a few of the more popular ones: ereader, aportis, plucker, isilo, (protein data bank (no, seriously))
Luckily for the most popular of them (ereader and Aportis) there are easily available tools to reconvert them to html or txt.
Here is a (full?) list of those pdbs