As a hobby this summer I have an old computer I want to turn into a web server, not for anything serious, just something to mess around with.

I have already set up the machine with the apache server itself, but I'm having trouble making it accessible from the web. I can connect to it using localhost, and if I use the IP address I get from whatismyipaddress.com I can see the site, but if one of my friends goes to the same address, they can not get through.

At first I thought I configured the NAT settings on my router incorrectly, but I connected my machine directly to the internet and have the same problem. Is there any way to see if I'm behind a NAT router at my ISP's end?

If I'm behind a NAT at their end, is there anything I can do about it other than purchasing a static IP?

And if not, is it possible that my ISP is blocking incoming connections? Online games and bittorrent work fine so incoming connections seem ok. I'm not sure how or why they would block someone from setting up an http server.

Is it also possible that I've done something wrong at my end? I have unblocked port 80 for all incoming connections on my software firewall and other people behind my router can go see the site ok so I doubt I set up the server wrong...

If you're connected to the internet via a dsl modem, It may have a NAT firewall built in that also has to be considered.

I'm not connected via a modem, I have Verizon Fios and there is no modem (at least on my end)

It's quite possible (likely, in fact) that your ISP is blocking requests for port 80 on your machine - you might want to contact them or check their terms of usage to be sure. Many ISPs don't allow clients to run web servers without charging you extra for the "privilege"

Could I use something like port 8080 instead to get around this?

That might work. At the very least, it's pretty easy to check. If 8080 doesn't work, you could also try some odd non-standard port as well.