UNetbootin writes Linux distributions onto a USB stick. It carries a built in list of 29 distributions and 12 system rescue tools, accepts an ISO you already have, and ships a separate installer for each of three platforms.

A small optical toolbox that packs burning, image conversion and bootable USB creation into an installer under 6MB. It covers CD, DVD and Blu-ray, reads the common image formats, and stays free for personal and commercial use, with a Pro edition for the extras.

A disc image utility for Windows that reads ISO, BIN, NRG, IMG and DMG, edits the contents of an image without repacking, burns to CD, DVD and Blu-ray, and writes bootable USB drives. One-time licence covering several machines.

An open source writer for installation images: choose an image, choose a drive, press one button. System disks are hidden from the list, and every write is read back and compared. Same interface on Windows, macOS and Linux.

A boot tool that changes one assumption: the stick is prepared once, and afterwards you copy system images onto it like files. Several of them can sit side by side and be chosen from a menu at start-up, with no reformatting between.