FormatFactory is an ad-supported freeware multimedia converter that can convert video, audio, and picture files. It is also capable of ripping DVDs and CDs to other file formats, as well as creating .iso images. It can also join multiple video files together into one. FormatFactory supports the following formats:
Video Formats:

3GP (.3gp)
MPEG-1 (.mpg)
Matroska (.mkv)
Flash Video (.flv)
SWF (.swf)
MPEG-4 Part 14 (.mp4)
Audio Video Interleave (.avi)
Windows Media Video (.wmv)
RealMedia Variable Bitrate (.rmvb)
VOB (Video Object) (DVD file) (.vob)
QuickTime File Format (QTFF) (.mov)
Audio Formats:

MP3
Ogg
Wave Sound (.wav)
Adaptive Multi-Rate (.amr)
Windows Media Audio (.wma)
Advanced Audio Coding (.aac)

Picture Formats:

.JPG
.PNG
.ICO
.BMP
.GIF
.TIF
.TGA