Especially for incoming webhooks, it would be nice to override the BOT tag text that is shown on every message. This would allow (for instance) integrations to post to a channel as a user in the external system with the name of the system shown instead of BOT, e.g.:

someguy IRC: hello

or

myusername JIRA: issue comment

There would still be a visual indication that the username is associated with an integration and may not be an actual user, but the word BOT isn't always the best description of what's happening.