I assume your project is the site you talked about in an earlier submission. If that is the case, here are a couple of observations:

The site looks very clean and I think another one or two ads would be ok, as long as they are relevant and of high quality. The current ad for screen protection is a good example.

I find the search to be a bit confusing. I would putting "type" at the top would help. I thought I had to choose a brand first, as it was not immediately clear to me that the categories are independent. I would rather search for a black leather case than for a case made by i-nique.

Use A/B-testing to evaluate changes to the site.

Random ideas: become an affiliate of a company that makes customized cases. Enter the itunes affiliate program, add a badge with the iPad app of the day or something similair. Make a dedicated site if one the non-case products gets a lot of traffic, e.g. an ad for screen protection.

I'm intentionally a bit vague because you didn't name the site. You might want to post the URL to get more answers.

Edit: added some more concrete examples.