Hello, I noticed there is no plowshare package in ArchLinuxArm, but since I think a decent download station cannot live without it, I managed to get it working.
You need to make your own package, so first follow http://archlinuxarm.org/developers/building-packages.
Then refer to AUR plowshare page: http://aur.archlinux.org/packages.php?ID=24601 and download the PKGBUILD.
Install the listed dependencies, all but js (which is missing in ArchLinuxArm); install spidermonkey instead.
Edit PKGBUILD and look for 'depends' section; replace 'js' with 'spidermonkey'.
You can now create the package with makepkg and install it with pacman.
Tested and working, js and spidermonkey are mostly compatible.
Bye and happy download