If it is awkward and embarrasing all round, why not suggest that you all club together and do something good. For example, you can buy a cow for someone in Africa (via Oxfam). Or just support a local charity. The gift of helping someone else less fortunate can be much more rewarding than struggling with what is the appropriate amount and gift for people you don't know, who probably won't want it. Discussing what to support for your communal Christmas charity can also work well for team spirit. If you don't want to do it that way, let each person put the charity of choice on a slip of paper and simply draw one out.