Ask HN: Constructing a viral loop for our B2B2C social app

Hi HN, we (re-)launched our startup about 3 weeks ago, here (http://news.ycombinator.com/item?id=1988016) and we have been getting an okay response from our users. We have had a couple of sales so far. However, being bootstrapped, we find it difficult to keep the market's attention via continuous PR/publicity or CPC marketing. Clearly, we need a good baked-in, inherent viral mechanism to allow the app to spread organically. Like Jason Cohen said, virality has to be baked-in, not bolt-on. Currently, we are doing a few things to construct an inherent viral loop, keeping in mind that we are a consumer-facing group deal app, but to be sold to online retailers: 1) Plastering our brand name on the widgets of our free trial users (retailers use us, generate awareness among competitors, competitors use us, generate awareness among competitors, and so on...); 2) Plastering our brand name on Facebook posts, link shares, etc.; and 3) Making users share deals to participate in deals (we're a pay-by-Facebook-Likes group deal app). Are there other things that we can do?