you cannot advertise for free buddie.. what you're doing here is soliciting .. remember one thing there is nothing ' Free ' in this world.. what u can do is u can get exchange links with websites posts in forums without posting your website links use em in your sigh ,i.e signature and stuff like that =)
I agree that you wont get your add on any of the realy good sites and from what I know link exchanges are pretty useless unless you can find sites that are related to your theme. Remember that in link exchanges you will be linking mostly with people like yourself. If you only want to get your site out there and seen on other sites then go with a link exchange. If you want quality and pr then try to find a diffrent route. What we do is write a general letter and send it to sites we would like to see our logo on and then mail it to them. We havent had to many responses but we have had a few.