either to be able to have a yearly/monthly option set for directory structure (just like you can Include Network, Make Folder, etc)
-or-
[Advanced] button where you can use identifiers to specify the naming format like maybe a root directory (as is now), with up to (say 5?) boxes that can include either fixed names or identifiers, and each box would be a directory name (if not left blank):
(root) D:\Logs\
(box1) $network
(box2) $asctime(yyyy)
(box3) $asctime(mm-mmmm)
(box4)
(box5)
Network AnyIRC, todays date (2004-04-47)
Would create log files in: D:\Logs\AnyIRC\2004\04-April\

Okokok, maybe I sounded confusing, but I hope the example will make the idea clear.. Just somethin that will give better control over where the logs are saved at.
or to make it simple, the same idea as being able to change the timestamp (where HH is replaced with the hours, etc)... "D:\Logs\$network\yyyy\mm-mmmm\" or something along those lines.