Wings of Flurry and Maw of Chaos are uncapped, giving you potentially unlimited damage...
Unlimited damage potential*
Actual unlimited damage is impossible.
A typical build doesn't actually do significantly more damage with either of these spells relative to other spells of similar levels.
Circle Magic isn't a spell, it's an ability that allows you to boost your CL to 40, but it basically mandates you picking up Leadership to use effectively, so it's really not practical in games where that feat is banned.
There are actually a lot of 8th- and 9th-level spells that have their effect capped at a CL of 25. Nothing I can think of that actually goes higher.