Ringdroid

Open an existing audio file
View a scrollable waveform representation of the audio file at 5 zoom levels
Set starting and ending points for a clip within the audio file, using an optional touch interface
Play the selected portion of the audio, including an indicator cursor and autoscrolling of the waveform
Play anywhere else by tapping the screen
Save the clipped audio as a new audio file and mark it as Music, Ringtone, Alarm, or Notification.
Record a new audio clip to edit
Delete audio (with confirmation alert)
Launches automatically in response to the GET_CONTENT intent with a mime type of audio/ if any other application wants to pick an audio file - for example the "Rings Extended" application.
Assign a ringtone directly to a contact.
File formats

Supported file formats right now include:

MP3
AAC/MP4 (including unprotected iTunes music)
WAV
3GPP/AMR (this is the format used when you record sounds directly on the handset)
OGG