1. All Bloggers United – This group is unique in that link up threads are topic related. When you leave a link, you choose which topic to file it under. This means that your post is much more likely to be seen by others who are blogging about the same thing as you. For me, it’s easier to go comment on blogs that are similar to mine rather than those that don’t fit my interests.
2. The Blogging Elite – This group has grown exponentially since it started. That means your content is being viewed by a lot of eyes. There are daily link and share threads. There is no “quota” to fill each day, which means reciprocation is built on trust and respect for other bloggers.
3. Bloggers Get Social – This group is a great place for asking questions. The bloggers here range in expertise, which means that you are likely to get an answer for any and all questions you ask. There are also lots of tips, tricks, and advice posted in this group. (P.S.–> let Krystal know I sent you!)
4. Her Campus Blogger Network – This group is great for girls who are in college or just out of college. I joined back when I first started my blog. I love the community that has been formed and the opportunities that this group provides. I do feel that I’m starting to get out of the appropriate age range for this group and will likely be moving on soon. (Eeek..30 is approaching quickly!)  In the mean time, I’m looking for something similar for my age group. I may just have to start my own group if I don’t find one.
5. Blog Bliss – This group is perfect if you want to get to know other bloggers without all of the share threads. This group is purely about sharing life and getting to know each other. It’s a place to find others that might understand your struggles with balancing life and blogging.
Are there any other groups I should check out? 
If I were to create a group for 20s & 30s, would you be interested in joining?