There is. However, the community hates redundancy, so a new, improved one might not be well received.Been thinking about this for a bit now..
Why don't we have a mod where the sole purpose is to alert users to update mods? It could be something like a splash screen as the user logs in, I've seen similar screens done already. There could be an API for the mod dev to send the version update number, how critical it is, and provide a link or download method with or without instructions on how to install it. You know, have a standardized method of alerting people.
As an average user, I'd love to know when other mods need updating instead of waiting for a new pack or keeping track of 100+ mods.
(although I wouldn't be against trying. Hey, if I can get someone else to work on the actual Minecraft portion, I'll help with the backend)