In reply to rginns: Go for it, post your details to any company you have an interest in.
I wouldn’t bother higher management unless that is the level of job you are looking for. In which case, use your contacts and network for all its worth. Far better to contact the Human Resources or Recruiting Department unless the company is too small to have one.
Send an up-to-date CV and a brief covering letter stating what you want; e.g. that you are looking to change careers and are interested in a job in.....asking them to keep it on file until a suitable position arises? And add a line or two about why they’d miss out if they didn’t consider you.
The CV should be brief, ideally two pages unless you’ve a great employment history and make sure it is tailored to the company you are contacting.