no-g.tk was just for fun, of course
Among the others, I think omdv.ml could be used for mailing lists (omdv ml = omdv mailinglist). omdv.cf (cf == config), maybe for pointing at articles on proper configuration on the wiki.
I don’t think .tk, .ga or .gq have any particular meaning, so I guess we could use all of those for general purpose stuff.