This is the best chess interface for *nix, in my opinion. It has LOT features and is very stable. But GUI looks dated.
If you want chess interface with more modern GUI for *nix, i recommend to look eboard or knights.
As of xboard 4.0.5 i think that it's a much better than gnomechess.gnuchess is not as clear on the visualizalation part.
An open, cross-platform journaling program.
A scientific plotting package.