it is really a good point to discuss to The process of mashup is highly effective and you can always encourage someone to use your content or tools to promote their services. Make sure to add a back link to your website. RSS is a worthy idea to try with.
Quality outbound links will help you to get better visibility in the long run. This will add value to your website and you can actually become a user resource.
It is highly appreciated to reward valuable users of your website. Give them the due credit and acknowledgement for their services. Rewarding is the best thing to be done in order to win trust and confidence.