The Grumpy DBA blogs . . .

asm_diskgroups.sql – nice format for diskgroups and available space originally from Jeff Hunter
asm_disks.sql – See disks used by diskgroups or available for use – originally from Jeff Hunter
drop_asm_db.sql – script which will prompt for a database name and prepare a script in the format “del_(dbname).sql” which can be run when the database is down to remove all files for that database in ASM.
asm_files.sql – script to list all the files for all diskgroups