Since Apple abandoned the idea of bringing native tv tuner in macs (Apple’s Consumer Performa Line, 1992 to 1997), mac users have been looking elsehere to enjoy live tv on the mac, here a list of solutions:

Miglia
TV Mini Express (£34.00)
Provides a simple and easy way to get tv in your mac. Watch, record TV, all in brilliant digital picture quality.

TVBook Pro Express
Digital TV for your MacBook Pro
TVBook Pro Express is a TV card specifically designed for Apple’s MacBook Pro. Enjoy live digital TV on your MacBook Pro, record to your hard drive, edit your favourite shows and burn them onto DVDs TVBook Pro Express comes in the form of a nifty ExpressCard/ 34 integrating a fully featured digital TV tuner. Bundled with The Tube software, TVBook Pro Express lets you watch, pause, rewind, skip forward and record digital terrestrial TV on your MacBook Pro.

TVMax+ (£128.00)
A TV tuner that let you Watch, pause and record all your favorite tv shows, also let you convert those recorded tv shows to Apple TV and Ipods on the fly. TV listing is provided by TitanTV.

ElGato
EyeTV ($149.95 USD )
Enjoy superior free-to-view digital TV (DTT, or Freeview) reception on your Mac deep indoors, in weak coverage areas, and on the move at speeds up to 160 km/h, all thanks to EyeTV Diversity’s revolutionary antenna diversity technology.

In Dual-Tuner mode, EyeTV Diversity becomes two conventional digital TV receivers in one, enabling you to watch one TV show and record another simultaneously.
Watch TV on your Mac
Rewind, fast forward, and pause live digital TV
Browse EyeTV menus in Full Screen mode with an Apple Remote
Record hours of your favourite TV shows directly on your hard drive and edit out unwanted content
Find TV shows and schedule recordings using the built-in Program Guide—includes a free one-year subscription to tvtv (where available) valued at 19.80 euros
Export clips and entire episodes to your video-capable iPod®, Apple TV™, and iPhone™
Store your collection on an external drive, or burn it to disc using Toast® 8 Titanium (not included)

HDHomeRun for Mac bundle ($199.95 USD)
The HDHomeRun is a centralized TV tuner that shares digital TV over your Ethernet network with any Mac in your home or office. Its dual tuners and included EyeTV software allow two people to simultaneously watch or record different programs from different Macs.HD HomeRun receives free over-the-air HDTV and Clear QAM digital cable.

WinTV-HVR-950 for your Mac or PC ($111.00)
Watch high definition ATSC digital TV or analog cable TV on your Mac or PC screen! ATSC HD is the over-the-air high definition TV standard for North America.
Easy to install: just plug into your USB 2.0 port.
Digital over-the-air ATSC TV receiver built-in. A portable digital TV antenna is included, to receive digital TV up to 10 miles from a ATSC transmitter.
Record ATSC digital TV programs to your disk drive using high quality MPEG-2. TV recordings will typically consume 5 Gigabytes of disk space per hour for ATSC high definition. The software uses in the WinTV-HVR-950 is ElGato EyeTV.