There's also the PostgreSQL Monitor, a Tcl/Tk application written by Bruce Momjian. It's under-advertised IMHO, I only know about it from the PostgreSQL lists.
It was available at ftp://candle.pha.pa.us/pub/postgresql/pgtop.tcl. I haven't checked if it's still there (sorry). Bruce mentioned that he would put it in /contrib, so maybe you can just get it from the ftp sites.
See this message for some details: http://fts.postgresql.org/db/mw/msg.html?mid=73573.
