Start with making a list of all those things you always said you would like to do if you had time, I'll bet you find plenty to keep you busy and have fun too!
besides the above:
read a good book,
breakfast/lunch with friends,
recipe searching on the internet,
take the dog and yourself for a walk, run, bike ride,
take a long walk to somewhere peaceful, scenic and quiet: just sit and admire all the beauty and enjoy the peace and quiet
take a class in something fun you have always wanted to learn to do
meet your husband for a romantic

lunch!
have your husband come home for a romantic

lunch
if you miss the kids too much, you can always volunteer a couple of hours a week to help out at school
Awwwww, Sassy you are always so busy and working so hard, just take a few days to enjoy yourself!

nice long soak in a bubble bath in the beautiful bathroom you and DH finished last winter