I would like to generate heat maps using microbial data collected on a spatially defined sampling grid. I am not familiar with any geostatistical tools. Could you advise me a nice software not to complicated?
I would suggest using R with the ggplot2 and using geom_tile
http://docs.ggplot2.org/current/geom_tile.html
If you are not familiar with R the hardest part will be reading in and organizing the data. The nice thing about R is that it is free and there is lots of help available online.