Merge multiple file types...?

[RoninV]

Any suggestions on a free app that will merge multiple image file (jpg, bmp, gif, tif) into one file? Not looking for a morphing type app, but one that will take multiple files and create one file. Though each image type has its one unique features, converting one to another can be done. In fact, I believe there are apps out that that can convert multiple image types to PDF.