There could be a lot of things you can do depending on the situation.
if the weeds are in a veggie garden you can over winter the plot by covering it with black plastic.
If they are in between a flagstone walk way, use a blow torch designed for this application.
There is a product called corn gluten which when applied at the right time of the year, stops weed seeds from sprouting in the spring.
Here is some info on corn gluten:
http://eartheasy.com/article_corn_gluten.htm
The $ is well worth it if you can afford it.
Please please please stay away from herbicides. They are so dangerous to animals, pets, small children and big ones too. they kill birds, turtles, frogs and every living thing that comes in contact.
hope some of this helps.
peace