We started working with this client back when our company was located in Florida and have maintained a close working relationship ever since, even after relocating to Virginia in 2001. Working with clients for this long makes us feel like we're part of their family, and they know they can contact us at any time and get a fast response. The fact that we've been working with them since their initial website launch results in our knowing not only all the workings of their site, but also all the history behind decisions surrounding the architecture, etc. Whenever they have had staff turnover in their IT department, they've known continuity was still there regarding their website and that's invaluable.
Since this client is a Florida state government agency, it's especially critical that their site has no downtime; state residents who need to make online payments on the day that a payment is due can't afford to deal with a site that's down, and the agency can't afford to have angry citizens. We're really proud of the level of service that we've helped them supply for all these years and they appreciate never having to worry about their site.
What kind of relationship do you have with your customers or clients? Are you getting to know them personally so they know they can rely on you when times are tough, or are you just worried about making the sale? If you'll take the time to invest in these relationships, you'll not only see the business payoff but will also get personal satisfaction from many of the relationships.
Ironically enough, though, the few clients who are no longer with us were pro bono jobs; I honestly can't think of one paying client who has left (other than situations like a business that has closed). For some reason it seems that it's human nature not to appreciate things that are too easily received. I'm sure there are some exceptions, but most of my business associates have had the same experience: when you provide a service for free or deeply discounted, even to a good cause that you strongly support, you should be prepared for the work not to be valued as highly as if it had been paid for. Sad, but true. A real-life example: one of my friends is a PR agent for professional athletes (I'm talking MLB, etc., not farm league). She had been doing pro bono work for a non-profit for over a year and finally had to notify them that she wouldn't be able to continue doing it; the Executive Director of the organization actually asked her, "do you know anyone we can pay to do it?" Obviously the organization placed no value on her services since she had been doing it for free. The message isn't to not try to help good causes, but to do so because you feel strongly about supporting the cause - not because you think you're going to get future referrals out of it.