It is possible to share a printer on a network. For example: two computers sharing one printer while the computers are connected to a home network (local Area Network - LAN). To share files between two computers, mark a folder or drive as shared - search Google on sharing files for more info.
Server Message Block (SMB)
To share files; to share resources such as printers or DVD drives; to connect each computer to the Internet; to share messages with one another.
network port
Networks are, by definition, a mechanism that allows users to share files with each other; the only additional requirement is that each user that wishes to share data must be using compatible protocols.
Workgroup
You can use a wireless network (WLAN) to share Internet access, files, printers, game consoles, and other devices among all the computers in your home.
share files via bluetooth
It is easy to share using IP Protocol via eathernet
Bear Share is a free site that allows users to upload music and video files to share with other Bear Share users, and to download music and video files for personal use on a mp3, iPod, or other music player device.
Samba.
Networks allow the sharing of files, printers and other resources. Networks also allow an administrator to control the security settings on all computers which are connected to it through Active Directory.
Sharing printers between Macs and Windows PCs is quite doable and should not present any major problems. Apple support has information about possible problems. (See links below)