Return links! Courtesy links! I have found some webmasters think you are being downright impertinent to suggest some sort of quid pro quo in this context. A goodly number understand and link back to me. Fortunately.
It is how the internet works.
What was that comment about the insular, the small world? Narrow minds?
Thankfully there are at least some of those that echo our genre's characteristic.

If someone gives you a free service is it free, not "without value".
show you VALUE IT.

Link back.

Chris - Still waiting to see how well my submissions work.