6-9 mos was really rough for us. SO much going on developmentally, and the start of teething, combined with an ear infection, bad cold, and the flu. Yeah, it was rough. He did start crawling at 6 months, pulling up and cruising at 8 months, and first steps around 9.5 months. Oh, and that was our worst sleep period. A good night was only waking once an hour. Most nights he woke every 15-30 minutes. He was fighting sleep worse than ever.. screamed anytime he thought we were trying to put him to sleep. Naps were all over the place. I think I had a little PPD, I was a mess. We went for a LOT of drives for sanity.
Scared yet?

The good news is, around 9 months things slowly started getting better. Our turning point was a 'vacation' trip with my DH's family, including Liam's 5 cousins ages 6 and under. We didn't have our rocking chair (previously the only way to get him to sleep was to wrap him up and hold him very tight and rock him while he screamed) and we had to find a new way to put him to sleep. So the first night, I nursed DS on the bed, and then DH walked him around the room. He was asleep in 2 minutes, no tears. It was amazing. Liam loved playing with his cousins, he got WORN OUT! Lots of outside time as well. He even took his first steps during that trip. I learned a lot about Liam during that trip. He needs lots of interaction/stimulation during certain parts of the day. He needs outside time. He needs "excersize." He goes to sleep easier for his Daddy. He needs a routine to the day.
Things got better from there. His naps became longer and more predictable. I was able to nurse him in bed and he'd go to sleep. I could NAP WITH HIM! He didn't fight going to sleep every night. He started sleeping 1-2 hour stretches, and even a 3 hour stretch every now and then. He was HAPPIER! He started walking full time around 10.5/11 months and has just been a much more pleasant kid since then. He is busy busy, into everything, makes a mess, just all over the place in general. But, HAPPY. Now, around 12 months we hit another sleep regression (molars) and it didn't get better until about a month ago... and then this last week it has gotten bad again. But, we're almost done with teeth, so I see a light at the end of the tunnel!
I agree with the other PP's about babyproofing as much as you can, and letting them explore their environment. My mantra is-- as long as he is not hurting himself or anyone else, I'm ok with whatever he is doing.