Ubuntu Geek posted a tip on how to fix the GPG error for http://extras.ubuntu.com maverick Release
Problem When you try to access ubuntu extras you might see following GPG error W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extras.ubuntu.com maverick Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192Fix for GPG error: http://extras.ubuntu.com maverick Release
