Crow Canyon Internships
Crow Canyon offers yearly 10-week long internships for students pursuing advanced undergraduate or graduate course work in archaeology, anthropology, museum studies, education, experiential education, and related fields.
Volunteer and work opportunities around the world from this database.
When I checked, IIE Passport listed 125 opportunities for budding archaeologists to study abroad. You don't need to provide personal information to do a search, although it does ask for some to help tailor what you want.
Minnesota Historical Society
The Archaeology Department conducts research on a broad range of cultural and heritage resources throughout the state. Opportunities exist to work with an archaeologist on long and short term projects to conduct field and/or laboratory research, computer analysis, collections research, site preservation, public interpretation, and/or historic research.
Student Conservation Association
This great site includes a number of recently added archaeological internships for aspiring archaeologists.
Opportunities world wide; searchable by country, which makes it a little dicey to find archaeology jobs or internships.
Work Abroad: University of Michigan
William Nolting of the U of M's Overseas Opportunity Office provides good advice and information about working overseas; a database of volunteer and paid jobs over seas as well.