Monitoring (both inside/outside) - What Do You Use?

I asked about this some time ago, but the landscape changes so fast.

What do you use for monitoring, where monitoring is both:

1. from the outside - such as ping, checking http, etc. There are a million products and external services (I like NodePing) that do this.
2. from the inside - getting status from the box from inside, like "did MySQL go down" or "was there a RAID event"