If you need to access WiFi hotspots or other WiFi services, you know by now that they are plentiful. And while many of them are free, many are fee-based. Rather than paying for each hotspot, consider an aggregator. Hotspot aggregators like can help reduce these costs, by charging a single fee for access to tens of thousands of national and global hotspots (along with providing hotspot-locating and login tools, and additional security).
The big cheese for aggregated WiFi these days is Boingo.com, offering service for individuals and companies. iPass.com offers access not only to WiFi but also to 3G, Ethernet, and even dial-up... but iPass doesn't sell retail to individuals, only to companies and resellers, and the iPass web site doesn't readily burp up resellers catering to the single-user markets.
AT&T and other mobile broadband providers have been partnering with various hotspot providers, e.g., with Starbucks, Panera, McDonalds, offering their broadband customers free WiFi access -- which makes sense, since it removes load from their cellular networks. And some of the wired broadband providers have made deals with WiFi providers for their users.
Many-to-most of these are the hotspots that Boingo and iPass are aggregating; so depending on where you're going, and who your wired or wireless provider is, you may already have access.
There used to be bunch of other WiFi, 3G, and dial-up aggregators, but most of them have been cyber-toast for years now.
The only likely other suspect I can find is Trustive.com, which offers a mix of pre-paid minutes and monthly subscription plans for WiFi, 3G, and combination. However, Trustive is Europe-based; their WiFi map claims less than 1,600 hot spots in the United States... and their pre-paid minutes plan appears to start at 15 pounds for 150 minutes.
While contractless, Boingo has historically had only per-month plans. However, recently Boingo has added additional plans, and additional ways to purchase service.
For iOS devices (iPhone, iPad, iPad Touch), Boingo now offers Boingo Wi-Fi Credits. Boingo Wi-Fi credits is a pre-pay plan... and you purchase credits via your iTunes account -- a one-hour session is $1.99, a ten-pack costs $19.99 and you get you an eleventh credit free.
Of course, if you're going to be using several hours of Boingo service, it makes sense to simply buy a month's worth of service, since the mobile plans start at $7.95 per month.