The envelope system: Friend or Foe?

Do you regularly use "the envelope system" of spending cash, or a method similar? I used this system last year...and was completely frustrated with the amount of change and stray money I had strewn throughout my purse. I then began using my debit card for purchases, and didn't have any problems, except that I wasn't really budgeting an allotted amount each month for spending. March has been my "envelope system" re-try. So far I haven't spent more than in my envelopes, though I have been switching money around in envelopes. Much of my "entertainment" money has gone to "food." This causes for a problem with this weekend's entertainment plans.

Do you have any advice about using the envelope system? What kind of budget system works for you?