bring down the terminal with the ~ key and type:
/callvote nextmap
/callvote kick aantipop
/callvote map_restart
/callvote map <mapname>
/callvote g_gametype 1/2/3/4 (?)
the terminal has tab-completion, try it!
a very useful link for the quake3 terminal magic is here:
http://q3console.planetquake.gamespy.com/variables.htm (see also commands)