What can I do with a lot of sage?
One of the most popular things I've seen sage used for is tea.  You just dry the leaves, steep as you would regular tea leaves (personally I like it with ginger root if I have some handy), and then maybe a little honey or lemon.  Sage is anti-bacterial, which is a nice bonus.

Meat-wise, I like to use sage with pork chops, either as part of a marinade or just chopped and rubbed onto the pork and then grilled.  Sage also goes great with chicken.  Roll the sage in your hands to release the oils, then either chop very finely or mash with a mortar and pestle.  Mix with a little salt and rub onto chicken breasts, and sautee in oil or butter (or grill it).

Veggie-wise, I think it pairs very well with sliced, sauteed carrots.  It goes very well with potatoes, try sweating some onion in a pan with a little oil or butter, adding some potato slices, and right before they're ready add fresh chopped sage.  It's also a great ingredient in stuffing, dried or fresh.

I had sage-laced cornbread once, it was pretty delicious.  Wasn't there for the making of, so not sure if there was any special preparation needed, but the end result was nice.  In fact, a friend of mine a while back who was a baker loved using sage in various breads, but baking is one of my weak spots so I can't really give you any specifics other than "this combination works, check Google for recipes" :)

At one point, I heard someone refer to what they called "sage fritters", which were basically sage dredged in seasoned flour and egg, then quickly fried in oil.  I did a quick search to find the source, and didn't see it, but did come across a very interesting idea: Sage and Apple Fritters (these are much more of a true fritter than what I first mentioned).

If you get tired of it while it's fresh and you're running around like a lunatic trying to find uses for it, there's always freezing.  I freeze or dry any large quantities of herbs at the end of the summer, there are a few methods available.  You can reference this question, I feel like there's a better one about specifically freezing herbs on this site but I can't find it right now.  The short of it is, some people have good luck freezing whole leaves as they are, some people prefer to chop them or put them in the food processor with some oil or stock, and freeze into cubes.  Both methods have advantages and disadvantages.

Alton Brown has a great method for drying described in this episode (text transcript).  Essentially, you layer an air filter (like you'd use in your central air unit) with an herb.  Place another filter on top, layer it again.  Continue as much as you want, then strap them all to a box fan.  Instead of weeks to months, you should have dried herbs in a couple days, max.  You can watch the video here, skip to about 2:30 in.   Bonus: the same episode describes his method of freezing herbs, that's about 1:00 in on the same link.

Speaking of Alton Brown, he recommends herb vinegar - you'll find how he makes it on the (text transcript) link in this paragraph.

There are also a TON of medicinal uses and has been used for thousands of years for various remedies.  Since this is a cooking site I'm hesitant to list them all (there are a lot), but you can read more about the most popular ones here, here and here.

This is non-culinary, but you can use it to "smudge", which is often tied to cleansing rites, but can also be considered just a simple incense/potpourri.  I had a hippie friend once whose house always smelled like smoldering sage.  More details can be found here.

Can you tell I grow sage and generally have an abundance at the end of the season?