Google Scripts for Sheets!

ExportCSV.gs

function onOpen() { create_menu(); }
function create_menu() { SpreadsheetApp.getActiveSpreadsheet().addMenu("Export CSV", [{name: "Export this sheet as CSV", functionName: "export_csv"}]); }
function export_csv() { display_text(make_csv()); }

function make_csv()
{
	var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
	var data = sheet.getSheetValues(1, 1, sheet.getMaxRows(), sheet.getMaxColumns())
	var text = '';
	for (var j = 0; j < data.length; j++)
	{
		for (var i = 0; i < data[j].length; i++)
		{
			text += data[j][i];
			text += (i < data[j].length - 1) ? ',' : '\n';
		}
	}
	return text;
}

function display_text(text)
{
	var app = UiApp.createApplication().setTitle('Exported CSV');
	app.add(app.createTextArea().setWidth('100%').setHeight('88%').setId('csv').setName('csv'));
	app.getElementById('csv').setText(text);
	var ss = SpreadsheetApp.getActiveSpreadsheet();
	ss.show(app);
	return app;
}

ExportJSON.gs

function onOpen() { create_menu(); }
function create_menu() { SpreadsheetApp.getActiveSpreadsheet().addMenu("Export JSON", [{name: "Export this sheet as JSON", functionName: "export_json"}]); }
function export_json() { display_text(make_json()); }

function make_json()
{
	var char_sep = '"';
	var result = '';
	var data = '';

	var data_range = SpreadsheetApp.getActiveSheet().getDataRange();
	var frozen_rows = SpreadsheetApp.getActiveSheet().getFrozenRows();
	var data_array = data_range.getValues();
	var name_range_array = data_array[frozen_rows - 1];

	result += frozen_rows > 1 ? '{"' + data_array[frozen_rows - 2][0] + '": [' : '[\n';

	for (var j = 0; j < data_range.getHeight() - frozen_rows; j++) 
	{
		result += '	{ ';
		for (var i = 0; i < data_range.getWidth(); ++i) 
		{
			data = data_array[j + frozen_rows][i];
			data = (typeof data === "string" && data !== "") ? data.replace(/\n/g, "<br/>").replace(/\r/g, "<br/>").replace(/\t/g, "\\t") : data;
			result += char_sep + name_range_array[i] + char_sep + ':'
			result += char_sep + data + char_sep + ', ';
		}
		result = result.slice(0,-2);
		result += ' },\n';
	}
	result = result.slice(0,-2);
	result += frozen_rows > 1 ? ']}' : '\n]';
	return result;
}

function display_text(text)
{
	var app = UiApp.createApplication().setTitle('Exported JSON');
	app.add(app.createTextArea().setWidth('100%').setHeight('88%').setId('json').setName('json'));
	app.getElementById('json').setText(text);
	var ss = SpreadsheetApp.getActiveSpreadsheet(); 
	ss.show(app);
	return app; 
}