One way to engage students in blogging activities is to have them create short audio recordings that serve as blog posts. Their recordings could be simple statements about what they've learned in your class or they could be full explanations of their thoughts on a news story. Students could also make audio recordings of interviews with classmates, parents, or people that they meet on a job shadow trip. The StoryCorps Question Generator can help students format interview questions.
There is no shortage of tools for creating audio recordings. The five that are featured in the playlist below are all tools that I've used with students at various times.
The tools featured in the playlist are Vocaroo, SoundCloud, Clyp.it, AudioBoom, and AudioPal.