To pass arguments, see this great writeup at Tusharm's website. I am working on a custom wrapper for the OnTime method that will utilize the methods Tusharm mentions along with some others. It seems like it might be of good use to a lot of folks out there...
Using procedures with arguments in non-obvious instances: macros associated with shapes, forms, and commandbar elements, and called by the OnTime and OnKey methods
As far as Excel returning information about what OnTime processes are currently active and the parameters they currently contain, I know of nothing. Like Eric stated, you would have to maintain a custom list of your various parameters. I'll post the OnTime addin when (if) I ever get it done.
Eric. These are the properties that the class currently contains. Any suggestion for more that you think might be useful?
Private pEarliestTime As Date
Private pProcedureName As String
Private pLatestTime As Date
Private pSchedule As Boolean
Private pLoopIntervalSeconds As Long
Private pLoopUntil As Date
Private pNextScheduledRunTime As Date
Private pActivated As Boolean
Private pItemName As String
Private pGroupName As String
Private pTag As String