Monitoring your server health

In continuation of the topic .

I will be brief: what, in your opinion, is missing such services as basicstate.com , host-tracker.com , mon.itor.us and so on?

Maybe you have your own software in your inventory, but would you prefer to use a service with more extensive functionality?
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Do you need diagrams and similar “complex” structures on such a service, or is it enough just to write about any problems with servers?

I'd like to hear the opinion of admins.