SayAndPost.com provides a tiny (192 kb) windows application that allows you to record a voice message and post it online immediately.
After recording you can just insert link to the voice file into your email, webpage or forum post. Your file will be stored on Say and Post server, so you don't need to get your own webspace.
SayAndPost.com offers two plans for storing your audio files : You get 10 mb web space and 100 mb monthly bandwith for the free plan. For 50 mb web space and 500 mb bandwith you only pay $11.95 per year.