Agile is certainly a good bet - I don't know of many/any teams working in an agile enviroment that don't have a healthy respect for the power of the team over the power of the individual. Pair programming, too, is likely to be a helpful indicator of how much time you spend day to day with another person.
I'd offer the thought, however, that non-Agile doesn't necessarily mean no-interaction. Here's a few other situations that may be high on the human interface:
- GUI designers and anyone who designs stuff in a highly collaborative environment with regular people (customers and/or users).
- Support people and trainers - people who are responsible fixing customer issues - usually have to collaborate with both customers, and other team members.
- Managers - not an entry level job - but one where your level of human interaction will go through the roof.
- Sales engineers - may or may not actually program - many do mock-ups and proofs of concept - to help convince the customer that what they want is doable.
- Professional services - often a lot more customer-interfacing than a pure product development team.
The key here is that the job can vary widely both in terms of interal vs. external communication. Some of these roles may have lots of human interaction, but they may not be everyone's cup of tea, because they may be mostly focused on communication with non-technical people - which may or may not be energizing depending on your personality.
I'd say the best indicator of all is to talk to the interviewer of any particular job. Although all the jobs I mentioned are usually high interaction, I can think of a case in point for each one where I've seen examples of the job having very little human interaction, due to the nature of the business or project.