Probably suggested before, too lazy to read through the whole thing, but...
Achievement Title: Ring Collector
SRB2Points: 10
How to get it: Collect 500 cumulative rings
Comment: Shiny...
Achievement Title: Ring Obsessor
SRB2Points: 50
How to get it: Collect 1,000 cumulative rings
Comment: My precious...
Achievement Title: Ring Hoarder
SRB2Points: 100
How to get it: Collect 1,000,000 cumulative rings
Comment: Get a life.
Achievement Title: Ring Madman
SRB2Points: 10,000
How to get it: Collect 1,000,000,000,000,000,000,000,000,000,000,000 (One Decillion) cumulative rings
Comment: I bet j00 haxxed.
Achievement Title: Ring God
SRB2Points: 1,000,000+
How to get it: Collect 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 (One Googol) cumulative rings. For everyone 100 rings after that, you get one SRB2Point.
Comment: No seriously, j00 haxxed. It's impossible to count to this number, much less collect all those rings.