Instead of using a 3rd party application like NetPenguin or FireFTP to share files between machines on your Haiku installation, you can use a little tool included in Haiku call PoorMan. It's actually a webserver.
Fire it up, and it'll make a public_html folder in your home directory.
Under settings, select 'Send file listing if there's no start page'.
All you have to do is drop your files you want to share (i.e myfile.zip) in /home/public_html, get the IP address of your serving machine (you can get this from the desktop applet 'Network Status'), and mount that location or use a web browser to access the files: i.e http://192.168.1.1/
Additionally, you can link PoorMan to /boot/home/config/boot/launch to have it startup upon booting your machine.