Exercises for a limited dog?

My 9 month old dog has bi-lateral hip dysplasia so she's very limited in the work she can do. No intense things like agility, flyball or running hard.

Her walks are limited to about 10-15 minutes and are not too strenuous.
She's an aussie cross and is a very energetic dog. She's been great with the limitations so far but somedays she just can't sit still for too long and I feel pretty bad as she just wants to run, run, run.

Occasionally I'll take her to a park or the farm and just let her goof around and enjoy herself (then gets metacam to keep her comfortable) but I can only do that occasionally as it's nice to just let her be a dog.

In the house we'll toss/roll the ball around for her to grab and since it's not a huge house, she can't run hard/fast but enough to get some energy out both mentally and physically. Tug o war is another game she loves, and we also keep her occupied with bottles to whack around/gnaw on. But I'd love to have some extra exercises to mix things up with her.

We're going to start consistent swimming activities soon, but the more suggestions the better!

As a note;
She's on 500mg of glucosamine twice a day and is looking/feeling very good. You wouldn't know she had an issue except for a slight hitch in her step, but that is more due to when she broke her leg at 4 months old.

Clicker games can help with mental stimulation.

As for activities, you can try rally. In novice there are no jumps, nothing hard. The only problem I can see would be repeated standing and sitting, but if she's okay with walking/standing/sitting/laying for 5 minutes, she can get through a rally course. It's a lot of fun. One of the dogs in the class I was in actually completely dislocated one hip a year ago and had to have an FHO, and she was doing great.

Do you have a place to let her swim? My lab/border collie has an old ACL injury, which in her old age is causing arthritis, and she absolutely cannot run or jump anymore. But she can swim!

My sports medicine vet highly recommends swimming exercises. Aside from that, the mental games the others suggested. There's really not much else in the exercise department that is low impact.

I'd look for puzzle toys, especially the ones with food inside (like a "Buster Cube" or similar device). These usually help keep them occupied.

I was also going to suggest swimming but I see you're getting started on that! That will be an excellent way to burn energy but without the impact of running. You might want to start training her a bunch of "fun" tricks and then put together little routines to do, mixing up all her tricks! That will keep her brain active.