General:
* Co-author
* Co-dependent
* Co-education
* Co-exist
* Co-founder
* Co-host
* Co-ordinate
* Co-operate
* Co-owner
* Co-pilot
* Co-produce
* Co-sign
* Co-star
* Co-worker
More Specific:
* Co-evolution
* Co-habitation
* Co-insurance
* Co-founder
* Co-payment
* Co-signatory
* Co-sponsor
* Co-terminous
* Co-worker
Prefixes combined with "co-":
* Co-operation
* Co-ordination
* Co-existence
* Co-dependency
This is not an exhaustive list, but it gives you a good starting point for understanding the prefix "co-" and its various uses.