Redmine

It would be very useful to be able to add drop down list's for custom fields with selections that you could enter yourself in the admin interface e.g.

If you had a custom field called "Site" and added the possible entries "Site A", "Site B" and "Site C". the drop down list would only show those entries and you would be limited to select one of those entries or none

As an extension to be able to select multiple items would also be very handy.