Open PS2 Loader and FreeMCBoot mostly. Though you can burn the elf to a CD and launch it using the modchip; given I won't charge a dime to install it there aren't any downsides beyond it using ~4mb of space on the memory card. This can be shaved a bit by getting rid of the ESR files since you clearly don't need them. FMCB will also let you launch any elf file off the memory card and I want to say USB memory sticks but you might have to launch something to be able to load up elfs off a USB stick. Cheap and easy way to test stuff if you're a developer or at the very least negating the need to burn a bunch of CD-Rs after crafting a specific disc image to run the elf.

Personally I use most games off the harddrive to speed up loading times and the modchip to play games that OPL and HDLoader can't handle such as MGS2:Substance.