QTam Bitmap to Icon is a small icon converting software. It converts many bmp files to ico files by only four steps. 

IconMasterXP is an icon converter. It converts 13 different image formats(.PNG, .BMP, .WBMP, .ICO, .TIF, .TGA, .PCX, .WMF, .EMF, .JPG, .JP2, .PNM, .PSD) into Windows icons and has some advanced editing features and wonderful special effects.

Icon Constructor is an icon converter which can convert JPEG, BMP, GIF, PNG, PSD, PCX, TGA, SVG and TIFF formats into Windows icons. Make a pretty style for your icons easily with Icon Constructor styles.

GetIcon is a small software which can view and save all icons that reside in binary files like DLL, EXE, and many other extension. This is a freeware application.

It's a free plugin for Photoshop and can make Photoshop an icon editor. Photoshop can open the .ico files and save image to .ico files with icon plugin.