In another topic I found xymonau explaining where to find pictures that are wanted.
Then I came across the RGB homepage with featured the latest searches.
Wouldn't it be nice if there was a section that displayed the wanted photo topics and subject? The search feature can be used for that, any image that has 0 results or a low amount of result get's a topic or something and the ones that have the lowest value get displayed.
I don't know however if it's possible with the available techniques. Don't know if it's possible to relate different search words with each other.