any other ideas?
Im asuming that your focusing on indie game budgets. The best way and basicly the only way is free social networks. This is the moast effective way. EVER. The key thing is to do it right. A great example of doing it wring is to create a facebook page, eaven spreading it among your friends is ineffective because it will only bounce around. A great way of doing this the right way is to post it as a topic on reddit, forums and a place ive found working extreamly well: 4chan.
There is simply no other way for indie developers. Sure you could market in the public but you wont reach many apropriate gamers, if you reach any at all. Create a working game, post it on a free board (reddit, 4chan) and if it deserves
to succed it will. Make it good, make it available
and if it is worth playing it will market itself.
Basicly look at the best example out there, a game taht i dont realy like but hey, its just my opinion: MINECRAFT
Read up on that games strategy and you will find everything you need to know.