The Esri Dev Meet Up is a "technical social" where developers can meet and discuss all things geospatial, geolocation, spatial analysis, and GIS. Developers of all levels of expertise are welcome. It's right after work, it's free, and we've got food and drinks for you.
Here is our developer website (http://developers.arcgis.com/en/) where you can learn more, download and code against our APIs for free, check out apps and code samples, and use cloud-based storage and web services to support all kinds of mapping capabilities.