I'm looking for recommendations for GIS blogs ... specifically GIS *developer* blogs. I'm less interested in the geography than in how apps are put together.

I'd like to keep up with ESRI ArcGIS as well as open source tools.

Which blogs are you fine people reading?
['https://gis.stackexchange.com/questions/32293', 'https://gis.stackexchange.com', 'https://gis.stackexchange.com/users/9795/']
To read relevant Open Source GIS blogs in an integrated way, visit <http://planet.osgeo.org/>

It aggregates more than 120 blogs, among them many developers' blogs (Tip: use j/k keys to navigate easily).
Not always GIS/Map related, but still interesting nonetheless. It's written by a few developers at the New York Times and focuses more on design and prototyping of interactive maps and graphics, and not necessarily GIS applications. Seeing their processes has been really helpful to me. They also use R a lot for spatial stuff, which is cool.

[Chartsnthings](http://chartsnthings.tumblr.com/)