> *foo=*[0-9]* should do what you want.  What are your
> other filters?  Do you have a -*foo=* above

WildCardFilters=-* +*index.php*cat=*[0-9]* +*thumbnails.php*album=*[0-9]*
+*displayimage.php*album=*[0-9]* +displayimage.php*fullsize* -*sort=* -*.jpg
-*.gif -*.png -*.css -*slideshow*

With this filter httrack happily includes URLs like
.../thumbnails.php?album=topn&cat=0 which to me seems buggy.