Is there anything stopping you from hosting them on their own subdomains (e.g. tutorials.yourdomain.com)? It's usually easier to configure multiple apps that way.

Quite simple if you're using Nginx as a reverse proxy in front of Nginx, just setup a specific Nginx location context for your non-Ghost directories. Examples can be see on my Ghost blog at the following for my sitemap

http://ghost.centminmod.com/ghost-sitemap-generator/

location ~ ^/(yournonghostwebappdirectory) {
root /yournonghostappwebroot;
}

Easiest way to add non-Ghost stuff to your Ghost blog i.e.

http://ghost.centminmod.com/ghostinfo/
http://ghost.centminmod.com/themeforest/

:)