Check out
1899 and
18185,
1899 being the cheaper of these two, although there are many others also.
Their setup allows you to add additional numbers, other than your home number, to your account so that any calls you make from any of the other numbers (prefixed with 1899 or 18185) will be charged to your account.
The reason I suggested both is in case one of the places you stay at happen to use one of the services already, in which case you'd use the other. Personally I get away with just using 1899 & its worked fine over the last few years. Takes a bit of explaining initially to the friiends whose phone I use but I've had no problems so far.