NJection.LambdaConverter is an open-source .NET assembly for converting delegates resolved from methods/constructors to expression trees.
Website: http://www.njection.net/

Copyright 2009-2012 Sagi Fogel
License: NJection.LambdaConverter is distributed under the MIT License.

Included open-source libraries:
	Mono.Cecil
	ICSharpCode.Decompiler
	ICSharpCode.NRefactory
	ICSharpCode.NRefactory.CSharp

Samples:

Converting a static delegate

public class Program
{
	private static void Main(string[] args) {
	    var lambda = Lambda.TransformMethodTo<Func<string, int>>()
				.From(() => Parse)
				.ToLambda();            
	}

	public static int Parse(string value) {
	    return int.Parse(value);
	}
}

-------------------------------------------------------------------------
Converting an instance delegate

public class Sample
{
	public int Parse(string value) {
	    return int.Parse(value);
	}
}

public class Program
{
	private static void Main(string[] args) {
	    var sample = new Sample();
	    var lambda = Lambda.TransformMethodTo<Func<string, int>>()
				.From(() => sample.Parse)
				.WithContextOf<Sample>(sample)
				.ToLambda();              
	}
}

-------------------------------------------------------------------------
Converting a constructor

public class Sample
{
	public int Value { get; set; }

	public Sample(int i) {
	    Value = i;
	}
}

public class Program
{
	private static void Main(string[] args) {
	    var types = new Type[] { typeof(int) };
	    var ctor = typeof(Sample).GetConstructor(types);
	    var resolver = new ConstructorResolver(ctor);
	    var lambda = Lambda.ResolveConstructorTo<Func<int, Sample>>(resolver)
							.ToLambda();            
	}
}

-------------------------------------------------------------------------
Converting a generic delegate

public class Program
{
	private static void Main(string[] args) {
	     var lambda = Lambda.TransformMethodTo<Func<string, DateTime>>()
				 .From(() => Parse<DateTime>)
				 .ToLambda();           
	}

	private static T Parse<T>(string value) where T : struct {
	    return (T)Enum.Parse(typeof(T), value);
	}
}

-------------------------------------------------------------------------
Converting a custom delegate

public class Program
{	
	private delegate int CustomDelegate(string value);

	private static void Main(string[] args) {
		var lambda = Lambda.TransformMethodTo<CustomDelegate>()
                                 .From(() => Parse)
                                 .ToLambda();           
	}

	private static int Parse(string value) {
		return int.Parse(value);
	}
}