Is there a device that converts any AC frequency to 60 hz?
As noted by several people AC->DC-> AC is the easiest way and would be the most normal.

But - 

Cycloconverter - Olde tech system - something to think about for the more technically informed. 

However, if your wind-turbine AC frequency is always high relative to AC you can get a moderately good result by using what is known as a cyclo-converter.

This is an option that I have not heard of being used in the domestic WT market and which is usually associated with high powers or Olde technology BUT
 a Cycloconverter could be extremely easily implemented at good cost in the 100 Watt - 30 KW size range with modern electronics. 

It is stated in a number of places on web that Honda use cycloconverters in some of their portable motor generator units. This is not certain but may well be true as this would allow them to use high frequencies with consequent reduced size magnetics and would also allow a degree of frequency stabilisation. I had noticed the very small size of their units wrt power levels and wondered what magic they had worked. 

A cycloconverter takes the available waveforms and compares them to a reference desired output waveform. It then draws power from the waveform that is closest to what is required. 

Waveform distortion obviously occurs but if the relative frequencies are high and multiple phases are available, quite modest output filtering may produce an acceptable result in many cases. 

An advantage is the efficiency can be very high, as the "best" alternator phase is simply being switched to the output at any time and losses are mainly switch (typically MOSFET) dissipation losses plus switching losses. Switching losses are modest as even at 10:1 input to output frequency switching rate is only around a few kHz. (Multiple switchings per output cycle mean switching rate is > N x fout)

The diagram below shows basic operation with 3 phase in and 1 phase out. A major advantage is that because input and output float relative to each other, and given input phase can be instantly inverted in polarity relative to the output if requried. This significantly increases the number of waveform segments to choose from and thus the available spectral purity for a given input:output arrangement. 

Multiple input phases are required to choose from - the more the better. As WT's often have 3 phase output and may have more this method may be a good match to the requirement. (The available number is effectively increased by polarity inversion - see below). 



From here

Technical comment - not relevant for questioner:

This is very B.O.T.E. but seems OK - 
Variable input frequency is easily handled with some effect on spectral purity. As long as rate of change of frequency is small compared to frequency this would not be a major problem. Typical loaded rotor inertias would usually make this not an issue. eg in the diagram above fin_3 phase is about 3 x Fout_1 phase. The shortest time period between switchings is about 10% of fin. The longest is about 25% Fin. If fout = 50 Hz then time period of longest segment ~~= 1/(50 x 3 x 10 ) =  &lt; 1 mS. WT prop at say 3000 RPM = 50 RPS = 20 mS per rev = 20 times longest segment . Blade inertia needs to be such that blade speed does not change vastly over say 1 revolution. If WT rotation rate doubled in 1 second (wow) then speed would change by ~= 2%/revolution = OK.

Note that the above deals with frequency but not Voltage changes. In many cases an AC-DC-AC system will be preferred due to tye freedom i gives to alter bith frequency and voltage.

Wikipedia - cycloconverters

[Book, 1972, MIT pressThe theory and design of cycloconverters

About 20 page paper UoTK, Knoxville. About 2000 Cycloconverter tutorial

Images linked to pages. Many many many ...