Nearly all of them! It saves your standard JPEG, PNG, GIF, MOV, and MPEG4, but it also saves a vast array of file types as listed below:
JPEG (*.jpg, *.jpeg, *.jpe, *.jiff)
GIF (*.gif)
PNG (*.png)
BMP (*.bmp, *.rle, *.dib)
TIFF (*.tif, *.tiff)
ICO (*.ico)
Camera Raw (*.tif, *.crw, *.nef, *.raf, *.orf, *.mrw, *.dcr, *.mos, *.raw, *.pef, *.srf, *.dng, *.x3f, *.cr2, *.erf, *.sr2, *.kdc, *.mfw, *.mef, *.arw, *.nrw, *.rw2, *.rwl, *.iiq, *.3fr, *.srw)
Photoshop (*.psd, *.pdd)
PCT File (*.PCT, *.PICT)
MOV (*.mov, *.qt)
MPEG4 (*.mpg4, *.mpeg4)
AVI (*.avi)
WMV (*.wmv)