HiveBloPoMo means Hive Blog Post Month (or something like that) and is a challenge set up by @traciyork to encourage people to post every day for the month of April. I think there are two per year and the next one is in November but you put the tag #hiveblopomo in each of your post.

It's more to generate content and activity on the network but it's also a good way to grow your account and meet other bloggers (if you can find the time to do all of that on top of 3D life haha)!