OpenArena is a free, cross platform and open source game based on the spectacular Quake3 game engine. The game is a bit rough around the edges, and not all features are utilized (ie background music) but the game play is very fast and intense. The game, sounds, graphics will certainly get better with time.
To use the pk3 file below you will need to download it and place it in the OpenArena 'baseoa' folder. For linux users this will be '~/.openarena/baseoa/', for Windows it will be the '/baseoa' sub-folder within the installation folder. There is no need to extract any of the files, just place the pk3 file and you should be able to access the extra 5 crosshairs. The crosshairs themselves are nothing special, I am just trying to learn / use Gimp for graphics :)