Hi all,

We've released a new API method that allows you to query for a tag and
return the clusters (and tags) associated with it.

http://www.flickr.com/services/api/flickr.tags.getClusters.html

There is no pagination for this method as the number of clusters for a
single tag is capped at 5 and each cluster may contain between 1 - 50
tags (give or take).

For example, searching for "api" returns :

<rsp stat="ok">
<clusters source="api" total="4">
<cluster total="19">
<tag>fiori</tag>
<tag>macro</tag>
<tag>flowers</tag>
<tag>bees</tag>
<tag>insects</tag>
<tag>nature</tag>
<tag>animals</tag>
<tag>insetti</tag>
<tag>italy</tag>
<tag>natura</tag>
<tag>primavera</tag>
<tag>colori</tag>
<tag>spring</tag>
<tag>animali</tag>
<tag>honey</tag>
<tag>canon</tag>
<tag>naturalmente</tag>
<tag>closeup</tag>
<tag>italia</tag>
</cluster>
<cluster total="8">
<tag>bee</tag>
<tag>flower</tag>
<tag>ape</tag>
<tag>fiore</tag>
<tag>sunflower</tag>
<tag>girasole</tag>
<tag>yellow</tag>
<tag>giallo</tag>

</cluster>
<cluster total="16">
<tag>flickr</tag>
<tag>screenshot</tag>
<tag>flickrapi</tag>
<tag>mashup</tag>
<tag>flickrhacks</tag>
<tag>php</tag>
<tag>flash</tag>
<tag>yahoo</tag>
<tag>tool</tag>
<tag>slideshow</tag>
<tag>widget</tag>
<tag>application</tag>
<tag>software</tag>
<tag>toy</tag>
<tag>error</tag>
<tag>download</tag>
</cluster>

<cluster total="3">
<tag>googlemaps</tag>
<tag>google</tag>
<tag>maps</tag>
</cluster>
</clusters>
</rsp>

Enjoy!