OH god, I miss old Payon, that's where I started my whole RO adventure (made an archer in Beta).
Ummm, I miss these things:
Seals!
Cliff Sniping (only a very few places left now in RO where it can be done)
Claymore mobbing Rach Sanc with my Rogue, and then because I'd mobbed almost the whole floor, the server would super lag EVERYONE. This was back before the server got upgraded, and it was running off of Pand's internet. I was not the only rogue or hunter to do this crap too. Server would on and off lag real bad during anytime any of us were there leveling.
Zeny Knife not sucking: Made claymore mobbing more awesome.
Kasas without reflect
Evil Sanc healing you if you wore Evil Druid. Made mobbing banshees a heck of a lot of fun on Stalker with Bowling Bash.
Main things that came to mind. Might think of some WoE/PvP things later