The terms "incubator" and "accelerator" are a bit confusing because they are used to talk about very different programs to help startups.

A traditional incubator provides startup-friendly office space as well as services for entrepreneurs, such as coaching, networking opportunities, introductions to service providers and investors, etc.  One advantage of a traditional incubator is that you're working every day next to other entrepreneurs, so you can expect to get a lot of help from peers, as well as from the incubator's mentors and coaches.

Examples of this type of incubator in the Portland area: PSBA (Portland), OTBC (Beaverton), PIE (Portland) and the Tie Incubator (Hillsboro).

There are also "boot camp" programs that actually don't provide office space but that do provide mentoring/coaching and seed investments.  One example: The Portland Seed Fund.

And then there are places that provide startup friendly office space but not structured mentoring/coaching.  Example: NedSpace.