Last spring I bought a PLB (Personal Locator Beacon) which, in my opinion, is the best of all worlds. It is a 406 EPIRB with a 121.5 homer and transmits a GPS signal within 3 minutes of being activated. It is small enough to fit in my pocket and, rather than being associated with a boat it is associated with me. I use it on my boat, on others boats and whenever I am doing any outdoorsy stuff in the wilderness. Unfortunately they are a little pricey but I think I'm worth it.
Check out the ACR ResQFix: ACR ResQFix 406 GPS Personal Locator Beacon (unadvertised price)
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217