Help in choosing appropriate open-source license...

[Tony R]

Folks:

I've read through the FAQ and some licenses, but I am afraid I need some
more help in understanding this issue:

[1] I have a speech application server I wish to release open-source
[2] Ideally, I'd like to do it like MySQL does it - open source for anyone,
and charged for large companies. (Note that worst-case, I can drop this
requirement, because I feel it is a genuine step forward for the speech
application industry, and the benefits to the industry on balance exceed the
private benefit I may derive. Of course, I'd prefer not to.)
[3] The additional complication is that a large company can use the server
without ever distributing it, and there do not seem to be any open-source
license that deals with code that is run on a server-farm and not
distributed. There is no web  page - the only externally 'visible' portion
is the audio that the speech application plays out.

Can you recommend a license that could fit this case? Alternatively, are
there licenses in the works that might apply? If not, how do I go about
crafting such a license?

Much thanks...

--Tony