I have added an SQL console to the pgAdmin3 plugin "PostGIS viewer". It allows you to run SQL queries on PostGIS data in order to filter them or execute spatial functions on them.

I have written an introductory tutorial of the Dimensionally Extended 9-Intersection Model (DE-9IM) in PostGIS for a Qualitative Spatial Knowledge class. I share it in this post.

I have added a QGIS plugin to the PostGIS Viewer for building SQL querys allowing the results to be displayed as a new layer. The plugin is RT Sql Layer from the Faunalia's repository, extracting just its SQL Query Builder.

Due to some suggestions from Ivan Mincik and Iván Lizarazo, I have been adding a couple of functionalities to the postgis viewer plugin for pgAdmin. Now, it has raster support (PostGIS-WKTRaster) and a layer list widget for displaying layer properties. Additionally, some minor bugs have been fixed: antialiasing and map units detection.

A couple of months ago, Ivan Mincik released a PostGIS viewer for pgAdmin using the Python version of QGIS libraries. I have taken the source code to add some functionality: now, every new layer is added to the same application and the scale and cursor coordinates are displayed.