Almost every NetBSD user knows about pkgsrc, the equivalent of FreeBSD port system. You can use it on NetBSD of course, but also on other Unix-like OS like *BSD or Linux.
Besides that, there is also pkgsrc/wip, where new maintainers can practise their skills. It may be worth taking a look there, whether you want to contribute or to find a package not present in the main pkgsrc tree.
You also have pkgin, equivalent to FreeBSD's pkg.
Finally, Joyent proposes prebuilt packages for a variety of platforms.