a) Give you my company's status twitter feed credentials; when a genuine problem is discovered, post for me that a problem was detected. Post again once the problem appears to be resolved.
b) Let me point a domain at you and give me a public status dashboard. Publish various stats and statuses (based on options I pick; don't make me publish load time, but if I want to I could publish trended load time data) and allow me to post messages both via your web control panel as well as SMS. Don't bother setting up infrastructure for me to register my domain through you. Most companies already have their preferred domain name provider. Don't create extra work for yourself; just give me the IP addresses to point via DNS.
c) Regularly sent emails detailing status over the past week and month. Do not embed it inside a PDF attachment to the email. Once I set up the service, I hope I never have to go back to your site because my sites never go down. However, if I get an email stating the uptime % this week vs. last week, or the response time average of this month vs. last month, that prompts action on my part. Do not over-email!
d) When you send me an alert that my site is down, please include enough info. What site? What service (HTTP/HTTPS/whatever else)? Why did it fail, did it 500? 404? Time out? I've looked at a lot of monitoring solutions and many of their SMS notices just say "Haaay. Yer shit is down. kthx" which is very unhelpful when your SMS wakes me up at 4am.
e) When sending SMS, make sure it comes from a single predictable number. This way I can assign it its own tone on my phone. Bonus points if you tell me the number up front, or send me a confirmation SMS.
f) If you're offering "page speed" type metrics, make sure I (the customer) know where you're measuring from. If all of my customers are Canadian, and you're measuring from Australia... if it takes an extra 100ms for the page to load, I'd like to know before you bombard me with SMS.
Edit! g) Make sure it's clear in your reports/site what time zone I'm looking at. A lot of the smaller sites get this wrong. Either show it UTC or let me pick what TZ I'm in. Do not do silly things like trying to guess my timezone based on IP address.