Just tried this out. Very simple and friendly sign up and setup. Looks great so far and seems to serve its purpose well. I will mention though that it felt odd having a link in the main navigation (Malware Scan) take me to a different website. Having not been familiar with Sucuri to begin with, I wasn't sure if it was an advertisement and how it related to UpMonkey. Thanks very much!

Seems to work fine, but I got this when I added one of my sites:

  2012-11-30 03:10:25 OK: Site added: http://example.com (is up).
  2012-11-30 03:10:25 Warning: Site http://example.com is down.

I.e., it thought it was down, and notified me accordingly, but then shortly afterward it recognized it as up (which it was the entire time).

I like the design :) clean and simple.

Glad you liked :)