Rolling inside another party/group with an /invite X /roll 100 macro is old news, it doesn't DC anymore when you use multiple macros for seperate people in the raid but it still works on this level).
Let's add something to it though, let's say you want to roll to multiple people without them seeing different numbers (the serious downside to just using 5 different /invite /roll 100 macros). Easy enough.
/invite X
/invite Y
/invite Z
/invite V
/roll 100
Viola, everyone sees the same roll, but what if you want to do it to a ten man raid? Make a raid of your own (must be a raid, need the multiple spots) and make a macro for:
/invite person1
/invite person2
/invite person3
...
/invite person 9
/invite person10
/roll100
All 10 people see your potentially amazing roll. Due to macro space this wouldn't reliably work for groups over 14ish but if you use two macros the group will see only two different numbers for 25 mans.
Old topic but a new elaboration as far as I can tell, /invite sure is silly.