Notifs. for when a contact becomes Available, Unavailable and for when a new eMail via the associated Hotmail account arrives.

Notifs. for RTs, Mentions, DM.s etc

Notifs. for Song Title - Artist etc. (As done with MusicBee)
Notifs. for current video being played.

Would stop potential exploits

Local applications may be able to download malicious code, requiring a password may prevent this.

Add a configurable option that will show registrations for:

o Only active applications (current Snarl model)
o Applications registered during this session
o All applications

When an application first registers it should require approval from the end user, or all it's notification classes should be disabled by default

This was suggested awhile ago, but haven't heard anything about it in a while.

Current Snarl isn't support OSX Growl UDP Protocol not receive
TCP Protocol is Target isn't running Notification TCP Timeout Delay.
My English is poolish.

At present, notification can be placed only in the corners of the screen. I think it would be good to add another positions:
Screen center
Top center
Bottom center
Left center
Right center

Might be a good idea to set a character limit or height limit for notifications. This would prevent a single notification from taking too much space on the screen and also to prevent the notification from being partially pushed off the screen.

aMSN notification plugin for connected contacts.

That way the latest know version is always installed, simplifying the process for users.

If this is done, you could also remove all currently installed styles and extensions except the default, and provide a first run wizard that allows users to choose only what they want to install.

Aimp2 notification plugin