Specifically, where did you look? We would hate to suggest places that you have already checked. Also, what other requirements do you have? Your original question is a bit vague on essential details.
1)You can easily make a F to V with digital logic (say 74AHCXX). With clocked FF's, generate one fixed pulse every time the input frequency signal comes high. The average voltage will be proportional to frquency. Filter this to smooth the pulses. With a crystal clock and a separate power supply for the logic, this makes a pretty good F to V.
2) A phase locked loop (PLL) makes a good F to V. The input signal to the VCO is proportional to the input frequency.
You may be able to find integrated solutions to the above techniques in RF IC's.
Basically many F/V converters (at least older ones) use a one-shot with an on-time shorter than the shortest period of the input signal.
A LP filter on the output of the one-shot gives you a voltage quite proportional to the input frequency.
As IRstuff mentions, it might be an idea to create the one-shot in logic (for instance with a 74HC74, 1/4 74HC08 and a fast enough clock). This will give a much more stable result. (time, temperature etc.)
