I have just deployed by first website to appharbor. One problem I came across was pre-compiling the razor .cshtml file giving an error that it couldn't find the Nancy.ViewEngines.Razor.BuildProviders.dll assembly. The build provider is just referenced from the web.config file without a direct hard reference. I am assuming that, because the assembly wasn't referenced anywhere, it was not being copied to the appharbor output folder. Consequently when the asp.net compiler tried to execute, it failed because the razor build provider was missing.
The way I got around this was to reference the assembly in the web project. It now builds and deploys fine. But, it's a bit dirty and I wondered if there was another way to do it?