Delayed Growl notifications of RSS news update

Hi guys,

I've been testing Vienna, NetNewsWire et NewsFire, but there's one functionnality I haven't found in any of those well deisgned applications : delayed notifications.
Let me explain :
Say you open you news reader in the morning. You've got a whole bunch of rss updates you didn't check. In netnewswire, when that happens, a myriad of growl notifications pop up, at the same time.
What I'd like is those pop-up to be displayed one or two at a time, so that the flow of notifications get put on a FiFO( first in first out) queue.... See what I mean? Know any way of accomplishing this, with the apps I'm already using, or another one, or by some handmade tricks?
If so, I'd be glad to hear from you!

Thanks!