There are several lists availble to aid with creating dropdowns, filters, links, etc. Note that the 'test' API key only returns the first 10 results.

countries - http://worldofspectrum.org/infoseek/api/countries?X-API-KEY=test
distribution_status - http://worldofspectrum.org/infoseek/api/distribution_status?X-API-KEY=test
distribution_status_types - http://worldofspectrum.org/infoseek/api/distribution_status_types?X-API-KEY=test
roles - http://worldofspectrum.org/infoseek/api/roles?X-API-KEY=test
entry_types - http://worldofspectrum.org/infoseek/api/entry_types?X-API-KEY=test
machine_types - http://worldofspectrum.org/infoseek/api/machine_types?X-API-KEY=test
origin_types - http://worldofspectrum.org/infoseek/api/origin_types?X-API-KEY=test
protection_schemes - http://worldofspectrum.org/infoseek/api/protection_schemes?X-API-KEY=test
turn_types - http://worldofspectrum.org/infoseek/api/turn_types?X-API-KEY=test
spot_reference_codes - http://worldofspectrum.org/infoseek/api/spot_reference_codes?X-API-KEY=test
features - http://worldofspectrum.org/infoseek/api/spot_features?X-API-KEY=test
themes - http://worldofspectrum.org/infoseek/api/themes?X-API-KEY=test
series - http://worldofspectrum.org/infoseek/api/series?X-API-KEY=test
control_types- http://worldofspectrum.org/infoseek/api/control_types?X-API-KEY=test
clones- http://worldofspectrum.org/infoseek/api/clones?X-API-KEY=test
title_features- http://worldofspectrum.org/infoseek/api/title_features?X-API-KEY=test
competitions- http://worldofspectrum.org/infoseek/api/competitions?X-API-KEY=test