EntAgent -- by Tyler Coffman. (AKA) [BDS] KungFuJesusEntAgent is a tool for map-makers who map for source-engine based games (HL2, etc...). EntAgent allows you to edit entity info(keys, outputs) with a text editor, so that you don't have to use the cumbersome hammer entity dialog.
basically, first you run your vmf through EntAgent, thus creating the .eal file. then, you edit it your text-editor of choice (I reccomend Notepad++) you can configure keyvalues, and connections in the eal file. then, when you're done, you can apply the .eal file back to your map file(.vmf), to finalize the changes.
NOTE: this software is currently in Alpha, and may be possibly unstable. Back up your vmf before you apply an eal file to it.