As you say Walks it does depend on the organiser and on the nature of the night, it also depends on whether the artist would expect to be paid for their spot or indeed how much. I only asked because you mentioned below that should someone wish to offer you a paid gig you would be happy to take them up on the offer - hence my question as to why someone should take that chance on you etc

But as I suspect everyone else on this board knows you are correct word of mouth, myspace (usually by using myspace as a demo rather a promoter randomly coming across someone on myspace), can all help in getting a gig/support slot etc but this varies from club to club, venue to venue, place to place, audience to audience