As LMiller7 said it may be illegal I live in Canada and found this on Wikipedia
Legality of piggybacking - Wikipedia, the free encyclopedia
Under Australian Law, "unauthorized access, modification or impairment" of data held in a computer system is a federal offence under the Criminal Code Act 1995. The act refers specifically to data as opposed to network resources (connection).
In Canadian law, unauthorized access is addressed by Section 342.1 of the Criminal Code of Canada. According to Section 342.1, "Every one who, fraudulently and without colour of right" obtains "computer services" from an access point is subject to criminal charges. (See Criminal Code of Canada, RSC 1985, c. C-46, s. 342.1 (1) (a))
Section 326 may also be used to address unauthorized access of a computer network. '(1) Every one commits theft who fraudulently, maliciously, or without colour of right', '(b) uses any telecommunication facility or obtains any telecommunication service.'
In Toronto in 2003, a man was arrested with a Wi-Fi enabled laptop in his car, partially undressed. He was tapping into unprotected wireless networks to download child pornography. Ultimately, however, he was charged not for piggybacking, but for the pornography instead.
In Morrisburg, Ontario in 2006, a man was arrested under section 326 of the Criminal Code of Canada. Ultimately the arrest was poorly reported, there does not seem to be any information available with regards to conviction.
The Computer Misuse Act 1990, section 1 reads:
(1) A person is guilty of an offence if—In London, 2005, Gregory Straszkiewicz was the first person to be convicted of a related crime, "dishonestly obtaining an electronics communication service" (under s.125Communications Act 2003). Local residents complained that he was repeatedly trying to gain access to residential networks with a laptop from a car. There was no evidence that he had any other criminal intent. He was fined £500 and given a 12-month conditional discharge.
(a) he causes a computer to perform any function with intent to secure access to any program or data held in any computer;(b) the access he intends to secure is unauthorised; and(c) he knows at the time when he causes the computer to perform the function that is the case.
In early 2006, two other individuals were arrested and received an official caution for "dishonestly obtaining electronic communications services with intent to avoid payment."
There are federal and state laws (in all 50 states) addressing the issue of unauthorized access to wireless networks. The laws vary widely between states. Some criminalize the mere unauthorized access of a network, while others require monetary damages for intentional breaching of security features. The majority of state laws do not specify what is meant by "unauthorized access". Regardless, enforcement is minimal in most states even where it is illegal, and detection is difficult in many cases.
Some portable devices, such as the Apple iPad and iPod touch, allow casual use of open Wi-Fi networks as a basic feature, and often identify the presence of specific access points within the vicinity for user geolocation.