This site doesn't come with "getting started" instructions, so here's the quick start --
There are many text strings on these pages which don't look like links, no matter what your browser settings (at least in IE8). If moving the cursor over the text causes the text to change appearance, it's a link. (Some of these are a little buggy; the page just jumps around. I think these are mostly broken links.) Read links do change in appearance, which is handy when scrolling through long lists. The whole site is largely text-based and virtually devoid of graphics, which helps it load fast.
The main page
http://www.university-directory.eu / will take you to a listing of countries on the bottom left, and a listing of academic fields on the bottom right (number of jobs in parenthesis). All are active links.
Be aware that this site is really a meta-list of lists from other sites; you will sometimes have to click through a few links to get to the actual job, depending on how the original post was set up. Occasional glitches are inevitable -- outdated links, links to wrong job, etc. Links may take you to a Web site which clashes with your browser, or loads slowly, etc.
Clicking on any field link will get you a short list (no more than 50) of jobs in that field, worldwide. In the upper left pane you may see the text "More Academic Jobs in ..." which is a link; clicking will toggle between the short list and a longer list. The banner across the top will indicate how many jobs are currently showing, and the total number of jobs.
The site is run out of Germany, and a disproportionate number of links are in German, for jobs in Germany; however, I have found several jobs openings in the USA that showed up on this site, but not on any of the usual USA-based sites. Other languages and scripts may appear as well. (Sometimes the home institution will have a Web site with an English option -- look for a British flag icon -- even if the job posting is non-English.)
The site underwent some changes recently, without explanation, AFAIK. The list no longer is sorted with most recent at bottom. It is not obvious to me whether the short list is the 50 most recent or not. Also, a couple of job referral services (experteer.de and stepstone) have begun massive data dumps of listings which don't always seem to be academic jobs.
Back on the main page --
Clicking on any country link will get you a list of institutions; institutions that have job openings will be marked with green text, and you will have to click on each institution link. Unless you're interested in a specific institution or city, this is probably the slower way to go. Might be helpful for those seeking a term/year abroad.
I've only used this site to search for jobs in Chemistry; if you have a different experience please post any helpful hints. There is actually a whole lot of info at this site besides jobs -- I haven't even begun to explore it.