[jamesbritt]

such a licence would not be considered an open source or free software licence by the OSI or FSF.

So what? What's the downside of using a variation of a common license that is not approved of by the OSI or FSF?

Someone other than the target excluded group might not use the software you're offering for free?

Who would get mad if I released code under the MIT license (or some variant) with an additional requirement that it cannot be used to build Web sites the advocate killing abortion doctors?

If it's my code can't I just set whatever conditions I want (modulo the requirements of any prior licenses my code may be bound by)?

[rmc]

Oh yes, you can release your code under whatever licence you like. The problem with not using an Open Source Licence or Free Software Licence is that it's harder for other people to build on your work, and your work might not be included in distributions of free software (e.g. Debian).