Able Batch Converter does exactly what its title suggests, allowing you to easily convert multiple graphics files at the click of a button.

More than that, you can also edit images directly in Able Batch Converter, to produce a variety of effects (rotate, flip, resize, mirror, auto crop, filters, noise remove, deskewing, watermarks, margins, color enhancements etc).Image files you can convert from:
JPEG Bitmap (jpg, jpeg, jpe, jif)
PaintBrush (pcx)
Windows Bitmap (bmp, dib, rle)
TIFF Bitmap (tif, tiff, fax, g3n, g3f, xif)
CompuServe Bitmap (gif)
Windows Icon (ico)
Windows Cursor (cur)
Portable Network Graphics (png)
Windows Metafile (wmf)
Enhanced Windows Metafile (emf)
Targa Bitmap (tga, targa, vda, icb, vst, pix)
Portable Pixmap, GrayMap, BitMap (pxm, ppm, pgm, pbm)
Wireless Bitmap (wbmp)
JPEG2000 (jp2)
JPEG2000 Code Stream (j2k, jpc, j2c)
Multipage PCX (dcx)
Camera RAW (crw, cr2, nef, raw, pef, raf, x3f, bay, orf, srf, mrw, dcr, dng, arw, rw2, rwl ...)
Photoshop PSD (psd)
Adobe PDF format (PDF)
PostScript (PS, EPS)
Adobe Illustrator (AI)
Kodak PCD (*.pcd)
DICOM (*.dcm;*.dic;*.dicom)
DR HALO CUT (*.cut)
AVS (*.avs)
Kodak Cineon (*.cin)
Graphviz DOT (*.dot)
SMTPE DPX (*.dpx)
FITS (*.fits)
FlashPIX (*.fpx)
HDF (*.hdf)
Matlab (*.mat)
MIFF (*.miff)
MTV Raytracer (*.mtv)
Palm Pixmap (*.palm)
HP PCL Printer (*.pcl)
Apple PICT (*.pict)
PIX (*.pix)
PWP (*.pwp)
RLA (*.rla)
Irix RGB (*.sgi)
SUN Rasterfile (*.sun)
Scalable Vector Graphic (*.svg)
TrueType/Postscript font (*.ttf)
VICAR (*.vicar)
Khoros VIFF (*.viff)
XBM (*.xbm)
GUMP XCF (*.xcf)
XPM (*.xpm)
JBIG files