Let me preface this by saying I am somewhat of a newbie when it comes to marketing websites so please bear with me. My biggest site is 4 months old and seems to be doing pretty well: PR3, 600-800 uniques per day and about $300 a month in adsense revenue. I don't do any marketing at all other than listing it on some directories and other basic free link building methods. About 85-90% of my traffic comes from search engines or direct type ins and the rest of it is from links from other sites. Is there any marketing method I could use to increase traffic and possibly pagerank that is cost effective? It would seem like using adwords or some other similar advertising program would be counter-productive because I would pay too much per click. I don't know if the site type matters but it is pet related. Any idea would be greatly appreciated.