There are a lot of web hosting affiliate programs that offer good affiliate commissions. The bad thing about web hosting is that it's over saturated, but will always be needed as new sites increases on the web. There are many web hosting affiliate programs listed in the affiliates directory in my sig. There are also a good amount in some of the larger affiliate networks like ShareASale, CJ, etc.
You can also start your own affiliate program on your site using some software. I suggest using some professional software. To start with you can promote your aff program within your current clients, friends etc. Thanks.