If your list is called L, try:
R = QQ[apply(L, getSymbol)]
Here's an example:
i1 : L = {"a", "hello"}
o1 = {a, hello}
o1 : List
i2 : R = QQ[apply(L, getSymbol)]
o2 = R
o2 : PolynomialRing
i3 : gens R
o3 = {a, hello}
o3 : List
i4 : ideal(a^2 + hello^3)
3 2
o4 = ideal(hello + a )
o4 : Ideal of R
-Mike