- White Paper
- Testimonial
- Podcast Interview
- Nominate them for an Award
- Find a speaking opportunity for them
- Blog Post
- Link to them on featured client list
- Introduce clients to each other when they have a good fit
- Talk about them and send referrals their way
- Feature them in an enewsletter article or a print newsletter article
- Include in promotional video
There are probably many more ways to do this. If you think of another please add it to the comments.