Travelling in Europe:

by train:
http://ccl.kuleuven.be/~corn/railinfo.html
http://www.ns.nl
http://www.sncf.fr
http://www.sncb.be
http://www.bahn.de
http://www.sbb.ch

by train and by air: from France
http://www.voyages-sncf.com promo!!!

currency converter na Yahoo! (a good tool for Scandinavia and the new EU members)
http://finance.yahoo.com/currency/convert?amt=310&from=SEK&to=EUR&submit=Convert

by bus:
http://www.eurolines.com promo. There's a charge for online booking (around 3 eur)

by air (low cost & booking):
http://www.ryanair.com subscribe to their e-letter! they send info about all the promotions
http://www.transavia.com from the Netherlands
http://www.edreams.com (when you buy well in advance, you can fly Madrid-Paris-Madrid for 90 eur all incl. with Iberia which is not low-cost!)
http://www.ebookers.com
http://www.easyjet.com
http://www.go-fly.com
http://www.wizzair.com
http://www.sterling.dk
http://iceland.flight.is
http://www.myair.com
http://www.germanwings.com
http://www.avantix.ru (Russia-abroad-Russia, inside Russia)
https://www.flydba.com
http://www.billigflieger.nl
http://www.airberlin.com (to get there http://www.berlin-airport.de/EN) 

Where to sleep:
http://www.hostelbookers.com
http://www.hostelworld.com
http://www.hihostels.com


In Stockholm this place is good: http://www.hostelbedandbreakfast.com/
In Baden-Baden http://www.jugendherberge-baden-baden.de/

Some prices (as for October 2006):
1)France 12-25 carte 49 eur one year discounts (yourpassport-size photo, no address)
2)the Netherlands 55 eur one year discounts after 9.00 (no photo, your address: will be sent to your Dutch address, but you get a temporary card immediately)
3)Paris - Strasbourg 20 eur one way Prem's (buy in advance), normal price around 40 (travel time is about 5h). Now TGV available. (less than 2h instead of 5h)
4)Strasbourg - Baden-Baden 9.60 one way with 12-25, normal price around 12.60. buy return ticket in France, cause in Baden-Baden it's 9.75 one way with 12-25
5)Bruxelles - Charleroi 10.50 one way, 45 minutes by bus from the Midi train station
6)Skavsta - Stockholm 199 kr return ticket Internet (order online!) travel time by bus 1:20, buy here http://www.peopletravel.se/en/koncernen/
7)Beauvais - Paris 13 eur one way, 15 euro one way Internet (it's strange, right), travel time is around 1 hour by bus, buy in the bus return ticket when going from Paris, or at the guichet at the airport
8)Paris metro http://ratp.fr/ (September 2007) 1.50 one trip,  11.10 carne (10 tickets), 3.20 jeune one day (Sa or Su or holiday)
9)Stockholm metro+bus 60 kr 24h since you buy it at the tourist info office (one ordinary trip costs 20 kr)
10)Bruxelles tram+metro 4 euro one day
11)Bruxelles: Atomium it's easier to get there from the Midi train station taking tram #18 in the northern direction till the end stop than going by underground with changes
12)Strasbourg tram+bus 1.30 one trip  (one hour changes only in one direction, buy with coins from a machine at any tram stop)
13)McDonald's
Prices may be very different, the product line is similar. Try the Danon fruit&yogurt. Prices in Paris: 0.95, Madrid: 1.50, San Remo: 1.95, Strasbourg: 1.40 eur. WC in McDo: don't throw away the bill! You may find your entrance code to the WC. In Paris for free, Bruxelles: 0.30, Strasbourg: some are for free, some with a code on the bill.

You'll definitely need a VISA or MasterCard...