This is not a really technical question but is required for a system I am building. I am after a UK suburb/postcode database. I haven't been able to find this anywhere and wonder if it is available (freely). I know in Australia is is freely downloadable from Australia Post. Also a US suburb/zip database is required as a secondary concern.
Might be worth looking at Where can I get postal codes for all countries?
Accepted answer there was http://www.geonames.org/, but some other options listed too.