Cogito -- unmaintained since late 2006[1]
pg -- URL dead; web searches reveal no information
quilt2git -- URL dead; web searches reveal no information
(h)gct -- URL dead; no repository activity since 2007[2]

[1]: http://git.or.cz/cogito/
[2]: http://repo.or.cz/w/hgct.gitSigned-off-by: NEric Sunshine <sunshine@sunshineco.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>