Questions:
Are you restarting Apache after every change you make to the httpd.conf file?
Are you sure port 80 is blocked by your ISP?
Have you checked the syntax of you httpd.conf file? After you edit the file drop to the terminal and run:
sudo apachectl configtest

Anyways, looks like you've got some errors in your httpd.conf file. Try this:

code:

---

NameVirtualHost *
Listen 81
<VirtualHost *:81>
DocumentRoot /Library/WebServer/Documents/tiff
ServerName www.tiffanycalvert.com
<Directory "/Library/WebServer/Documents/tiff"
allow from all
Options +Indexes
</Directory>
</VirtualHost>

<VirtualHost *:81>
DocumentRoot /Library/WebServer/Documents/josh
ServerName www.joshazzarella.com
<Directory "/Library/WebServer/Documents/josh"
allow from all
Options +Indexes
</Directory>
</VirtualHost>

---

Let me know how it works.