A seperate memory storage for something like this, isn't very paractical I think. I mean, how long is the "temporary storage" going to last? For you, maybe a whole msn messenger session is enough, for others it would be too short, etc...
On the other hand, there is already such a storage system, called the quicktexts just as you said
. It is ideal for it...
The only thing you can't do yet is create a quicktext on the fly. But a small plugin would be ideal for something like this (and is exactly why the plugin system exists). You could create a plugin which makes a quicktext to store such stuff.
In that way, the temporary storage isn't something different and new, but something which last as long as you want and uses the existing "system"...
Thus, what I wanna say is: idea is nice, but I don't think a new storage system should be made or even a new command or something, all can be done with a plugin (which can even be configured to store it as a quicktext, or in it's own memory file or something)
/ 
