The primary advantage of using an Arduino bootloader comes from the built in libraries and support of the arduino community for program design. Simply solder or socket in the MCU to your board and load the program using the serial USB connection like any other Arduino project. Remember that using the IDE and properly you will need an external 16MHz crystal or resonator, a 5V supply, and a serial connection.
At present time the 1050-1019-ND is the only AVR part that has the bootloader pre baked. If you need to use the Arduino code with another AVR style chip then you will need to burn the bootloader first using a hardware programming method below. If you are looking for a list of MCU families that can use the IDE you would want to reference the Wikipedia list of Arduino boards and compatible systems.
If your program doesn’t need or doesn’t use the arduino libraries however you can expand your search space to the PIC and the (still Arduino compatible) Atmel AVR MCUs. In these cases a program can be loaded using ICSP (in circuit serial programming) or JTAG (Joint Test Action Group) methods.
In some cases Digi-Key is able to support the programming of these chips for you, so that you can load them into your PCBs without serial programming accommodations. In these cases we encourage you to look at our value added services index and reference the custom programming contacts there. This can be especially useful if you are paring your MCU to an external EEPROM and want to get either per-programmed using our infrastructure.
One the flip end, if you need the 1050-1019-ND but without the bootloader, take a review of ATMEGA328-PU-ND.