gistfile1.txt

void Main()
{
	var items = new [] {
	new[] {"A", "B"},
	new[] {"1", "2", "3"},
	new[] {"*", "+"}
	};
	
	//items.Aggregate((memo, i) => memo.SelectMany (m => i.Concat(new[]{ m}).ToArray()).ToArray()).Dump();
	
	var currentList = new List<List<string>>(items[0].Select (i => new List<string> { i}));
	foreach(var genArg in items.Skip(1))
	{
		var newList = new List<List<string>>();
		foreach(var currentItem in currentList)
			foreach(var newThing in genArg)
			{
				var newItem = new List<string>(currentItem);
				newItem.Add(newThing);
				newList.Add(newItem);
			}
		currentList = newList;
	}
	
	currentList.Dump();
}