What finally worked for me is what I found here:
http://www.codeproject.com/Tips/395286/How-to-Access-WAMP-Server-in-LAN-or-WAN
To summarize:
set Listen in httpd.conf
:
Listen 192.168.1.154:8081
Add Allow from all to this section:
<Directory "cgi-bin">
AllowOverride None
Options None
Order allow,deny
Allow from all
</Directory>
Set an inbound port rule. I think the was the crucial missing part for me:
Great! The next step is to open port (8081) of the server such that everyone can access your server. This depends on which OS you are using. Like if you are using Windows Vista, then follow the below steps.
Open Control Panel >> System and Security >> Windows Firewall then click on “Advance Setting” and then select “Inbound Rules” from the left panel and then click on “Add Rule…”. Select “PORT” as an option from the list and then in the next screen select “TCP” protocol and enter port number “8081” under “Specific local port” then click on the ”Next” button and select “Allow the Connection” and then give the general name and description to this port and click Done.
Now you are done with PORT opening as well.
Next is “Restart All Services” of WAMP and access your machine in LAN or WAN.