Thanks for all your answers that I've received so far.
Can anybody suggest how to export georefferenced image into geotiff file from output of GRASS or gstat ?
In general what I need is exporting bathymetry maps into formats compatible with MapInfo (that is a request from my customer 
).
I've got lost among their www pages so I just expect to find somebody here who knows how to transfer my maps so they can be read by MapInfo GIS software.
Besides, I have no experience with MapInfo 
at all.
Thanks in advance.
Viktoras