Image Eye can read a whole lot of different file formats:

Ext.	Format description
BBM	DeluxePaint brush.
BMP	Windows bitmap format.
CAL	Computer Aided Acquisition and Logistics Support format.
CALS	Computer Aided Acquisition and Logistics Support format.
CUR	Windows cursor.
DDS	DirectDraw surface.
DIB	Windows device independent bitmap.
IFF	Interchange file format.
FIF	Fractal image file.
FIT	Flexible image transport system.
FITS	Flexible image transport system.
GIF	Graphics interchange format.
ICO	Windows icon.
JIF	JPEG image file.
JP2	JPEG 2000 file format.
JPC	JPEG 2000 code stream.
JPEG	JPEG format.
JPG	JPEG format.
LBM	DeluxePaint bitmap.
MAC	MacPaint image.
NEO	Neochrome image.
PBM	Portable bitmap format.
PCX	PC Paintbrush image.
PGM	Portable graymap format.
PIC	PC Paint image.
PNG	Portable network graphics.
PNM	Portable image format.
PPM	Portable pixelmap format.
PSD	PhotoShop format.
PXR	Pixar format.
RAS	Sun raster format.
RAS	Computer Aided Acquisition and Logistics Support format.
RAW	Raw image description file.
RLE	Windows RLE compressed bitmap.
SUN	Sun raster format.
TGA	TARGA format.
TIF	Tag image file format.
TIFF	Tag image file format.

Write support however, is limited to BMP only.
If you want a format converter, then check out Any Image!