After playing with the ZAP [1] module for less than a half hour, having already installed YAZ [2] and played with SimpleServer [3], and seeing now that they've got a YAZ library built into PHP4 [4], I can now state unequivocally (or is that unequivocably?) that Indexdata [5] kicks some serious booty. There are doing as much directly for our community as any other company there is. Check out their stuff... it works.
Links:
[1] http://www.indexdata.dk/zap/
[2] http://www.indexdata.dk/yaz/
[3] http://www.indexdata.dk/simpleserver/
[4] http://www.php.net/manual/ref.yaz.php
[5] http://www.indexdata.dk/