You'll be able to see globular star clusters, such as The Pleiades and The Hercules Cluster. Under really dark skies, you'll be able to see some of the brighter deep space objects (DSO), such as the Orion Nebula, and the Andromeda Galaxy. However, you will not see much in the way of details, as 70mm is a bit too small to resolve them.
While star clusters will be fairly easy to see, the brighter nebulae will basically look like barely visible grey smudges, as will Andromeda.
Here is a link to a discussion thread on Cloudy Nights that discusses what you can see through a small telescope: