List of personal or corporate blogs that deal with VHDL or hardware design in general:
All major EDA vendors have their own HDL simulators. They usually support both VHDL and Verilog. Mixed language designs (designs that contain both VHDL and Verilog code) are also supported, but this usually requires a more expensive license.
The open source VHDL simulators have a much slower simulation speed than commercial simulators. Today open source simulators support a limited subset of VHDL