poor (and crippled!)

So, I wanted to do something fun (and get out of my college town) and cheap this weekend. it wasn't going to be too difficult..

except my friend sprained her foot last saturday so that rules our hiking/camping plan (and i'm thinking most outdoorsy things, she's on crutches!)

So....what can we do for fun that doesn't involve a lot of walking?

I'm thinking we'd have to scratch the whole trip idea and instead do one or two day trips somewhere..

we're in the sacramento area.

Go for a drive around Tahoe?
Go see Truckee?
Drive up Hwy 49 is also incredibly beautiful.
And Nevada City on 49 is so cool!
These are definitely all day trips, and they can be as cheap or as expensive as you want - just don't forget to pack your lunch.
You can still do outdoorsy stuff, there's things that are more about looking than walking. I did a quick google search, and there's a bridge in Sacramento, the The Franklin Boulevard/Thornton Road Bridge that has a large population of bats living under it. If it's anything like the Congress St. bridge in Austin, TX, when they come out at dusk, it's quite a sight, and completely free.
Really, be willing to act like a tourist. Go to a local tourist info and look up any free museums or such.
You'd have luck posting this to your own local community if you have one.

As for outdoor activities on crutches, depending on what they've done to their leg, see if you can rent canoes from your college's outdoor rec centre.
If you are into birding, there is a wildlife refuge up in Gridley. The American River Parkway and Discovery Park would be good as well. Find a spot park your car and pull out the binoculars.

Driving along some of the levy roads along the Sacto river can be nice if you don't want to go up 49 (it IS a beautiful drive and Nevada City is cool)

If you are of age Napa and Sonoma are nearby for wine tasting.
Go take a walk/limp around McKinley Park downtown, the rose garden should be blooming and it's beautiful. And not too big, and there are benches that you can sit on if your friend gets too tired.

I agree with the first commenter, come up to Tahoe! I live up there and a couple weeks ago a friend from Sac and I took a drive all around the lake and stopped at all the vista points and took photos of the lake from all sides, it was so much fun! Find a cheap hotel room (I run a motel, I'll give you a good rate :) and then spend the day on the beach one day.

In Sac, also, you could go to the Governor's Mansion, and there are a TON of parks all around that are free to go to. I used to go to a different park every weekend while I was living down there. Look in the News and Review and see if the museums are doing anything special for the weekend, since it's a holiday.

On Sunday's the Crocker Art museum is free from 10AM to 1PM, you have to pay for parking I believe, but it's not that much. http://www.sacmuseums.org/findamuseum.html There's info on all the museums in Sac there, even the ones you have to pay for are really inexpensive.
Fishing or doing a gentle boat trip (raft, canoe, or kayaks) should still be fine, if either of those are options for you. I'm not feeling creative enough to come up with much else, esp stuff that doesn't cost much money. :/
Go rafting or panning for gold on the American River. There are areas where access is easy, like at the historical point/park in Coloma.
Just a word of warning - I have done the "trip out on Crutches" things from both points of view, as a companion and as the unfortunate cripple. Even for the fittest and keenest soul on crutches moving around can be exhausting and frustrating. I was reduces to tears several times when I found that "that place is only another block on", or, having got there, discovered no level access. Worst of all is being stuck at the end of a long walk, exhausted, in pain, late in the day, with no way of getting back except the same long haul on one foot, over rough ground uphill...

Also remember that crutches make it much harder to carry bags, particularly if you are new to them - you may need to carry stuff for your friend.

Just be patient with us gimpy types, make sure you always have an non-walking escape route back from where you're heading - and if necessary accept that some stuff will have to wait until the next break when you have the full number of working legs between you.

Whatever you chose, I hope you both have a great weekend!
does she have a wheelchair? most public places will provide you with one to use.. if you go to a museum or zoo it could be fun. a big park could be easier terrain too. good luck & have fun!