Is there a way to add keywords to the product database (not on view to the customer) so that they can search for specific terms and bring up matching products.

For example i sell embroidery threads, i would like people to search through the threads by colours across ranges, would it be possible to put a field with a colour/s in the database that was searchable, and if so, how?

I hope this makes sense

I searched the OsC contribs page but couldn't find what i wanted but i'm sure a hack of the existing search code and changes to the database must be possible.

(i'm probably being too ambitious here... my normal problem)