What should I buy? Any suggestions?

Firstly, if you want a dog to run with you NOW, don't get a puppy. Puppies need to have their full growth before they run for extended lengths of time. That being said, get a terrier!  They have tons of energy and love to go, go, go.

I don't know exactly how big you want, but a small terrier like a Jack Russell (known as a Parson Russell in the AKC world) may be a good choice for you.  These little goys have energy to burn (think a small motor on caffeine!) and will play endlessly with kids. Another good small terrier might be a miniature fox terrier (these are UKC recognized, so you won't find any in the AKC ).

If you'd like something a little larger, a Fox terrier would be a good choice. There are two types, Smooth and Wire.  These weigh in at about 15-20 pounds and love to go as well.  They are a BIT more laid back than the aforementioned, but still have plenty of zip.

A medium-sized breed that MIGHT be good would be a Border collier. I say MIGHT because Borders are very high energy dogs who are also very, very smart.  They can NOT be left alone and only be exercised a short time each day.  A bored Border will "make work" for him/herself.  This may include herding the cat, nipping the kids (to herd them), peeling the siding off the house, leaping from chair to sofa to table, etc.  They need lots of mental stimulation and lots and lots of energy-burning each and every day.
As for larger breeds, you might look at a retired racing Greyhound.  These dogs are very, very sweet guys who are generally laid back at home.People are often amazed that they aren't more energetic when they are just hanging out.

Remember that if you do choose a terrier, these are feisty dogs.  Terriers are sometimes iffy with small animals since many were orginally bred as vermin hunters. If not, the dog is often the one who rules the roost! They can also sometimes be iffy with other dogs.  Terrier owners need to be just as feisty as their dogs.

I suggest a Springer Spaniel, they ae great dogs and love to run medium in size depending on the parents.
 
We used to have a Springer she was the best full of energy, Terrier is a good suggestion too. 
 
Maybe even a whippet they are small slender dogs love to run and are like lightening, but also love to hunt so rabbits beware!!![]    

Thanks for the great info...I was also researching the Pharoah Hound. Does anybody has any personal experiance they can share? Thanks

There is a Pharoah hound in my apartment complex. They are not small dogs by any means! Very tall and lanky. The few I have met seemed nice, but aloof- which can be typical for many sighthound breeds.

I know you said you want a small breed. But I suggest thinking about adopting a retired racing greyhound. They are large dogs, but sooooo laid back you will forget you have a dog in the house. While they don't NEED to run, they will really enjoy it. But most people's running speed is a light jog for a greyhound, lol! There are so many out there that need good homes.

As for a small breed dog that would be good for running with-- Go to your shelter and check out any dog that is in your size range. Ask about their energy level. I'd bet most of them would be willing to run next to you as long as you can go.

What about a whippet?  They are very very sweet and love to run.

I agree you should go to the shelter a pick a dog you like, and of those pups would really apprecaite a good home, and would most likely run with you.

a itailan greyhound would also work

I have a friend who recently got a haraoh Hound.  She calls him a Border Collie in disguise because of how intense he is.  This isn't someone that is new to dogs, either.  She's owned, trained and showns Boxers and Basset Hounds since before I met her.  As Lindsay said, they aren't small dogs.  The breed standard calls for males to be 23-25 inches, and females 21-24 inches.  Have you thought about a rescue greyhound (retired racer)?  Even tho they are about the same size as a Pharaoh Hound, everyone I've talked to who has them says they are big couch potatoes, yet love to run when outside.  I met someone at an obedience match once who lives in an apartment with 5 rescued greys.

Thanks for the great info...I was also researching the Pharoah Hound. Does anybody has any personal experiance they can share? Thanks

 
I'm owned by one, if that counts as personal experience.  They are incredible dogs.  If you do get one, make sure you interview the breeder for several reasons:  Breeders are starting to breed them oversized, taller than standards.  So the 55lb adult that you're expecting could end up being 27inches/shoulder and 75lbs lean weight.  Also they can be quite barky, as they love their voice.  They are quite charming yet retain their independence.  High energy level outside but somewhat calm indoors.  Mine gets along with the cat, who at 8yrs old had never been around dogs before. 
 
Also if you want a dog that follows directions all the time and won't wander off, try to escape, chase every leaf, squirrel, chipmunk, rabbit, moving object, light reflection, bee, fly..etc then don't get a PH. 
 
Pharaohs also are pretty serious most of the time, though when they're with the pack they will play at being silly and trying to make you laugh.  If you've any more questions you can contact me via private message or on the board, I'd be glad to help you in any way possible...(breeder contacts etc.)
 
-Ed

What about a Shiba Inu?

I don't think sighthounds, which are bigger than I think the original poster was looking for anyway, (Whippet, Greyhound, Pharoah Hound, Ibizan Hound, etc.) are a jogging type of dog. They need to have an open space where they can RUN at top speed, but in short spurts. What I've heard from sighthound owners is that the dogs will run at top speed for about 20 minutes a day and then turn into a complete couch potato and not want to move off their comfy bed the rest of the time.

Italian Greyhounds are in the toy group and I don't think they would be appropriate for jogging.

I'd recommend a dog that is bred more for endurance- Beagle, Brittany, Cocker Spaniel, and probably any of the Terriers. Good luck with your choice!