Which Software Can Open .eps and .ai Files?

EPS and files can be opened or imported with following applications (to name just a few)...

Vector editors like:

Adobe Illustrator
Corel Draw
Xara Xtreme
Inkscape

Raster image editors like:
Adobe Photoshop
Corel PhotoPaint
GIMP

Desktop publishing apps like:
Adobe InDesign
Quark Xpress

3D software like:
3D Studio Max
Cinema 4D
Swift 3D

Office Apps like:
Microsoft Office
Open Office

AI is native Adobe illustrator format and can be opened or imported by majority of applications from Adobe Systems Incorporated and majority of 3D applications and raster image editors.