To continue the recent theme of customized SWAT4 maps, there has been a new map pack released on SWAT4 wiki maintained by a guy named induktio which contains hundreds of SP and MP maps compressed into a 1.2GB torrent file. The maps are compatible with all versions and there are screenshots included from the original authors.
Of course, it is impossible not to mention the many other facets of this old website that are useful for SWAT players. There are sections on console commands and tutorials of creating your own custom map, as well as basic tweaks such as the ability to use special characters and colored names, skipping initial dispatches on Co-Op mode etc.
There are also downloads such as the Advanced Tactical Center, which "provides floorplans for all Swat4 and TSS maps, drawing tools to work out tactics". In summary, it is a very comprehensive site with a range of features that are sure to interest the common player.