I run a Linksys wireless G gateway with a few wireless compatible
laptops. It works well but i'd like to know if there's any products
available to increase the range of the gateway. Perhaps some sort of
booster?

Many thanks in advance,

Mark

Here are links to two such products:

http://www.linksys.com/products/product.asp?grid=33&scid=38&prid=629

http://catalog.belkin.com/IWCatProductPage.process?Merchant_Id=&Section_Id=201522&pcount=&Product_Id=136486

You can find additional information by searching google with  <
extending range of 802.11g network >.  
http://www.ezine.com/TechTips/ExtendingWireless.shtml  may also be
worth a look.

The best way to increase the range of your network would be to get
Repeaters. Linksys do a repeater series but not sure if they are
compatible with your existing Linksys kit:

There are a few repeaters on the market, the ones we know work are
Buffalo WLA-G54C and SMC2870W - ou will need 2 of theses units to
create a big wireless zone that will include roaming functionality if
you have a laptop.

these can be found at;
http://www.broadbandstore.co.uk/index.php?cPath=36

This site will also talk you through the setup if needed.

You can either replace the antenna with a higher gain unit or use a
external booster. Here are two examples of products.

2.4GHz wireless antennas for indoor networks:
http://xtremedevices.com/antindoor.html

Hawking 500mW Indoor Amplifier:
http://xtremedevices.com/hsb1.html

You should note that increasing the range of your network potentially
allows others to also access your network. Make sure you secure it!