Is there a programmer out there that will program both PIC(s) and Atmel miroprocessors? I work with both and would prefer only having one programmer.
Its theoretically possible but it would be messy because they use different programming methods. Far easier just to have two different programmers.
What is a good USB programmer to purchase for Atmel microprocessors?
Programmer for "Atmel" micro (I think you mean "controllers"), that is a broad statement. Atmel making many series of microcontroller. However, if you are talking about AVR and ATmega. I'm using AVRISP mkII. It works great!
I’m looking at it here. It doesn’t have a socket… So does it interface with the Diecimila?
I’d go for a USBtinyISP. Ladyada sells it.
Cheap, does a good job and you get to make it yourself.
I second the recommendation for the USBtinyISP. Ladyada’s also really quick to jump in with support if you need it.
Like the AVRISP mkII, it plugs into the 6 pin header on the Arduino or whatever board you may be using.