Webhooks for pmxbot. Read the source for details.
This lib provides a bookmarklet for readily sending messages to the pmxbot HTTP interface. To install it, just open /bookmarklet in the API service. It will present a link. Option-click the link and add it to your bookmarks. Give it a name like "Send to pmxbot".
To use the bookmarklet, browse to any web page, then select the bookmarklet. You will be prompted with a dialog with a channel and message. Specify the channel and optionally edit the message. Then hit Enter or click Submit and that message will be broadcast on the channel indicated.