"The 5 Minute Guide To Cheap Startup Advertising"
http://onstartups.com/tabid/3339/bid/43774/The-5-Minute-Guid...
3 part series on startup marketing, although this is more about retention than advertising:
http://www.softwarebyrob.com/2009/12/15/startup-marketing-mi...
http://www.softwarebyrob.com/2009/12/09/why-focusing-on-traf...
http://www.softwarebyrob.com/2010/01/12/startup-marketing-mi...