I think that an RP to IP converter would be a good addition to the store/interface so when people have 23 RP or something like that can convert it into IP. This could be used for if someone is just 46 IP off from 6300 IP for a new champion or a rune page. The left over RP could then be used for something instead of just sitting there. A 6300 IP champ is 975 RP so the IP to RP ratio of that is about 6:1 when looking at top tier champions. The RP:IP converter could work in a way that for every 1 RP you get, let's say 4/5/6 IP in return. Of course it couldn't be worth more than 6 RP because people would be able to abuse the system with ease.

I also realize that rune pages and a lot of champs don't follow that 975RP to 6300IP scale ex. Garen, Morgana, Lux etc but im sure Riot can figure something out, hopefully with some community input. Sorry if this question has been asked and/or addressed before but i think this would be a good addition to the game.