Custom search forms in Drupal
Genau was ich gerade gesucht habe;-) - views fastsearch und eine Erklärung von Robert Douglass.
It allows you to start with a view and narrow the set of content based on keywords. It utilizes the very search index that the search module has built, but it restricts its search to the content set defined by the view. It also uses clever SQL to do the actual searching quicker than the search module, thus the “fast” aspect.