I do alot of the stuff like you mentioned but I have a slightly more nefarious method that I've been thinking about trying.

There are alot of 'coupons' for Google AdWords. If you sign up for HostGator's $5/month plan, for example, you get a $50 or $100 (I forget which) voucher. If you buy the Google Analytics book (well worth the investment), you get a credit. There are lots of websites and services online. You could theoretically string these together to create a number of free advertising campaigns.

Of course, the catch is that you have to create a new AdWords account each time (most of the coupons are only for 'new' customers).