Merge mutiple groups script

I am working on a current scene which requires me to import a lot of .obj format files. They import fine, however due to the models very high poly count and complexity, I end up with literally up to one hundred separate groups. Its getting tiresome merging them or moving them under a central hierarchy and I was wonderng if anybody had a script that could do this ?
I’d appreciate any ideas. <!– s:) –><img src="{SMILIES_PATH}/icon_e_smile.gif" alt="" title="Smile" /><!– s:) –>