'3' UK have a new pre-pay proposition around making Skype calls from your mobile phone. They will allow you to make as many Skype calls as you want without any '3' charges and without requiring minimum monthly refills. You are, of course, charged (by Skype) for Skype 'dial-out' calls.
'3' Ireland also offer a pre-pay Skype call service but they force you to refill by €10 per month for this privelige.
Anyhow, the bargain alert revolves around the 3 'UK' Skype service since, if you can get your hands on a '3' UK SIM card (available on ebay), you will be able to use their Skype service in Ireland without any roaming charges thanks to the '3' UK 3 Like Home service.
The only catches are;
1. To avail of the free 3 UK roaming service you must roam on the 3 Ireland network.
2. The 3 UK '3 Like Home' service ends on 30th June 2009.