which sites are the most popular and successful for short term holiday
home exchange between Melbourne australia and european/uk and US
locations?
WHat sort of fees can we expect to pay? How do they check the bona
fides of offers?

The three popular and best known web sites for holidy exchange
worldwide are:

Intervac http://www.intervacus.com
According to the web site they are the worlds oldest home exchange
company. They have representative in 27 countries worlwide and offer
home exchanges in more than 50 countries. The only problem is that in
order for you to search the listings, you will have to subscribe.
Alternately, you can ask for a free information kit. The membership
fee starts from $65 dollars paid annually. Questions on how to check
the bona fides of offerings and other security concerns are adressed
at the following page:
http://www.intervacus.com/visitors/visitors.htm

HomeExchange.com
This web site has a very good industry reputation among its customers.
They guarantee that you will find a home exchange partner. I also know
a couple of people who are using its services for quite a long time.
Their services are offered worldwide including USA,UK and Australia.
You can search a comprehensive listings before becoming a member. The
membership starts at $49 dollars per year. Questions on how to check
the bona fides of offerings and other security concerns are adressed
at the following pages:
http://homeexchange.com/new.php
http://homeexchange.com/help.php

Home Link http://www.homelink.org
For their US site (http://www.swapnow.com)
Certainly one of the most comprehensive web site on the internet when
it comes to exchanging homes for holidays. Thay have seperate web
sites for many countrues. You can search for listings all around the
world including Australia, Uk and USA. They have 28 representatives
worldwide. Every one is able to preview a comprehensive information of
home listings. Membership fee is as little as $60 a year. I am not
sure how do thay check the bona fiddes of offers but some security
concerns are adressed at the sollowing page:
http://www.swapnow.com/info/home_exchange.html

Other useful web sites include:

http://www.exchangehomes.com (50 + countries)
http://www.dialanexchange.com
http://www.holswap.com
http://www.digsville.com

Another useful informative page is located at:

http://www.homeexchangeinfo.com

Google Search terms used:

"holiday home exchange"
"home exchange"

Hope, you will find the information useful.
Best regards,
leader-ga

Thanks ..sorry it has taken so long to rate. I have been checking out
the sites in detail.  I really appreciate a quick as well as complete
answer