California (not a country, obviously) is otherwise virtually comparable with Switzerland in this respect. Full constitutional amendments and legislative vetoes can occur via referendum.
EDIT: In practice, larger cities in California seem to have a comparable number of referendums as well. Unfortunately, they're all bundled into an election every 1-2 years rather than the Swiss system of elections every 3-4 months. This has its upsides, mainly in turnout which is still low in much of Switzerland, but also means many "less-notable" issues often aren't discussed in CA to the same degree that they seem to be here.