Reading the forums I see references to maps like Blaze and Fortress Siege but unless they are DMD maps, I have no idea how to find them other than clicking on random maps in the various Tormented/Alpha/Prospector maps.
Is there a global search function somewhere?
There's no global search funtion, but you can search the forum if it is a map posted on the forum.
If you see the name of a forum member, it is most likely an alpha map (Fortress Siege is a map made by Blaze and is located in the Blaze system (lower left) in the alpha sector). Anything with S100_X is prospector zone, anything with S200_X is tormented space and most other things are DMD or maps posted on the forum (check which forum board you are reading in).