bmp, if, jpg, png, ico, jng, koa, iff, lbm, mng, pbm, pcd, pcx, pgm, ppm, ras, tga, tif, wbmp, wap, psd
When you open an image, it doesn't have a toolbar or anything. You can open up a filelist, which displays the filenames of all of the pictures in the folder. You can also navigate by PgUp and PgDn, or the scroll wheel, and shuffle the picture order. Then you can also do a slideshow, and go to fullscreen. Overall, not a bad program.
The thing that I use bmap for is ICO files. Windows Image viewer can't view them, or Picasa, so rather than opening gimp every time, I set the file associations to bmap, and it opens my icons very quickly. Not a bad deal. Plus, it is open source. Somebody actually enhanced it by added scrollwheel support, and that's what I'm going to link to. But do realize that there is the original creator and be sure to thank him, if you want to thank somebody.