In the past when I have had excess limes, I have used a veggie peeler to thinly peel off the zest, and frozen that in a snap lock bag for future use. Then I juiced the limes and froze the juice in ice-cube trays. That way you have both the zest and the juice available whenever you need them.If you are cooking with lots of citrus, you can make use of the juiced fruit by making citrus vinegar to use for cleaning. Just get a large glass jar with a lid, pack in the juiced citrus halves and cover with cheap white vinegar. Let it sit for weeks to months. You can add extra vinegar and extra fruit as you go. When the jar is full and has "steeped" for a few weeks, strain and use the citrus vinegar for cleaning. i.e. shower screens, toilets, glass cleaner etc etc or as an alternative to fabric softener or dishwasher rinse-aid.
The best way to use up excess limes requires a bottle of tequila and shaker of salt.