Most of the better broadband ISPs will allow you to dial in also.
In the UK they won't offer a free number but typically you get a 0845 1p/min one or something like that. From abroad, you will likely need a different number to call, and it will cost as normal.
The problem is that you may not be able to dial in while the broadband connection is active (ADSL modem switched on) so you would need to switch off your ADSL modem when going away. Worth a check.
Another solution is a VPN back to your home PC; you just need
1) a router at home that supports a VPN (e.g. Draytek 2600/2900)
2) set up a VPN on a win2000+ PC (under 1 minute)
3) a fast internet connection (wifi or ethernet cable; GPRS works but only just) where you happen to be