If you want to travel around Europe or in the US cheap, you should travel by coach instead of going by train/by air. If you want to travel really cheap, then you should go with Megabus. This UK-based company offers travel to 60 destinations in Europe from as little as 1 euro/pound/dollar and also offers 30 destinations in the USA and Canada.
But even this low-cost travel can be made even cheaper (literally free) by using special promotion codes. These codes are offered by the company as an incentive to further increase its range of customers. One of the recent promotion was run in the US when Megabus offered free travel (with a 50 cent booking fee) for 200,000 people between 9th January and 28th February. Passengers only had to use the “TRYMEGABUS” promotion code at their online booking.
The codes can be found quite easily just by doing a quick Google search. There are many online forums and sites where the big offers are listed, so you never miss these deals. In the UK, some websites like moneysavingexpert.com, or ukhotdeals.com list available opportunities. There are dozens of other sites that offer specific travels for a specific period or to a specific destination. For example, if you want to travel from London to Amsterdam, you should just run a search on your destination with “Megabus” included in the search. Some results will definitely come up, with mainly those sites that offer “coupons” for Megabus’s special deal. Just follow those links and you can book the promoted journey.
Also note that Megabus runs a yield management model which means that the earlier you book your seat, the more likely it is that you can get it on the lowest price. So even without searching for a specific promotion, if you are quick enough, you can get yourself a seat for the lowest or almost lowest price available.