A different kind of link building strategy what I am thinking off. Please bear with me.
The model: You are optimizing your prime business website through which you will get the clients.
Beside all other options, you can think off this strategy.
1. Build a page on corporate social responsibility.
2. Towards Tax deduction, you can enjoy the benefit through giving a portion of your profit to a non-profit organisation.
3. Construct the page in that way. Give a link to that organization.
4. Build rapport with the organisation so that they must speak about your company as what you have done for them. May be a link and reputation at the same time.
5. You are getting values from engines.
6. Try to participate in fund raising web communities individually allowing links on the member page.
7. Time to time update the social responsibility page as what you are doing with the voluntary organizations. Spread this with social media.