Personally I'm in favor of open borders, ditching customs and passport checks on a global level, having a free labour market on a global level, letting people work and live anywhere they like and marry whomever they like regardless of nationality. Like the concept behind EU and US, but on a global level. I guess it's not realistic just yet, but I'm in favor of any step in the right direction, thus I support the expansion of the EU even if it may initially be a burden for the current crop of members. My best wishes of success for the newly formed African Union too. Hopefully EU, US, AU and others don't develop into a bunch of separate conflicting superstates but rather open up for a larger cooperation in these matters.