I am not really into connecting my A500+ to a PC (through a null modem) and then share Internet resources like that. I like the idea of connecing the A500+ to an 'old' hub more. However how would I connect my A500+ to the hub? As much as I know my A500+ does not have any place where to connect a telephone wire!
You'll need an Ethernet card and, as stated before, they're very rare for the A500. One that I know of is the Amiganet Hydra 500. I own at least one working model, they look like this:
http://www.easygalaxy.net/cfamiga/amiganet-hydra-500.htmlThe problem is that these use BNC connectors and not your regular RJ-45 UTP CAT5 cables that you're used to. So you'll need a switch or hub that supports both BNC and RJ-45 connectors or you'll need some sort of device that serves as an adaptor to convert signals from your BNC headed coax cable to the RJ-45 UTP CAT5 cable. I have one of those devices too and a 10Mbit switch that I used to try and get things working. In the end, failing to get things working I just gave up and went back to using a PPP/null modem connection to my iMac.
If you're really interested in a "standalone solution" your best bet would be to hunt down one of those RS-232 to WiFi adapters. You probably won't be able to use it out of the box without a gender bender, because the Amiga's serial port is DB25 female instead of the more usually found male. I'll be looking into buying one in the future (just for kicks), but they tend to be pretty expensive.
EDIT: Either that or hope that Jens Schoenfeld conjures up some cool addon that'll allow you to use your A500 with your WiFi network.
