All Paris underground lines operate on all Saturday nights and all Friday nights until 2:15 am.
To see the metro map : http://www.ratp.info/orienter/cv/carteparis.php
Don't hesitate to take buses, this is one of the best way to discover the capital. There is a great number of bus services, and many bus routes go through the centre of the city, along the banks of the Seine, through the historical quarters...
To see the bus map : http://www.ratp.info/orienter/cv/cartebus.php
Over 15,000 taxis are available.
A single centralized phone number to call all taxi ranks/stands : +33 1 45 30 30 30
Major taxi companies in Paris :
TAXIS G7 : www.taxisg7.fr
ALPHA TAXIS : www.alphataxis.fr
TAXIS BLEUS : www.taxis-bleus.fr
MOTO-BIKE TAXIS : www.city-bird.com
Batobus is a river-boat shuttle service offering (non commented) boat trips on the Seine with eight stops: Tour Eiffel, Champs-Elysées, Orsay Museum, Louvre, Saint-Germain-des-Prés, Notre-Dame, Hôtel de Ville, Jardin des Plantes. The service runs from end of March until beginning of January: from 10 am until 7 pm in March, April and October; until 9 pm in May, June, July, August and September; from 10:30 am to 4:30 pm in November, December and January. Boats come every 15 - 25 minutes.
To view the Batobus site : www.batobus.com
Paris offers 200 km of bike-only lanes, plus 70 km of bus lanes which can be used by cyclists.