I fairly commonly find myself in a situation where I would like to display one label for certain features and another for other features in the same layer. QGIS doesn’t have an official way to split labels up into categories, and until now I’d resorted to having two layers to render otherwise identical features. But, in the new, excellent expression based labeling from Nathan Woodrow, I realized one can use an SQL CASE statement. For instance, one time I need to use two types labels is when labeling roads in OpenStreetMap: I want to use the name tag, unless the feature has a ref tag defined (a name tag might be ‘Capital City Freeway’, while the ref tag would be ‘US 50’). Here’s how I solved that particular problem:

**Update 2012-02-02 17:57 -0800:I just wrote a post about another way to do this.

I really like QGIS. It’s a powerful GIS that runs on Linux (among other operating systems) and doesn’t require incredible amounts of CPU. One criticism I had of it was that it did not provide the same ‘click-and-go’ basemap experience one can get with ArcGIS for making simple maps (i.e. Add Basemap, select Bing, DeLorme, &c. and you’re done). No more! Thanks to the qgis-openlayers plugin available on GitHub, you can now use OSM, Google Maps, Yahoo Maps and Bing Maps as base layers in your project (side note: make sure you don’t violate any copyrights by using them). I’ve had a little trouble with the projections, but I’m not that good with dynamic reprojection in QGIS yet, so I’m sure it’s my error.; Unfortunately, the layers don’t support reprojection, so your project is basically forced to use Google Mercator—which may be a showstopper but is often acceptable for quick maps (remember, QGIS can reproject your other layers). If you do want reprojection, see this post.