"Heavens Above" http://www.heavens-above.com/main.aspx is a great resource for finding out what that thing was, or for getting notifications in advance of upcoming visible spacecraft fly-overs.
In particular, keep a look-out for the International Space Station and the "Iridium Flashes" in your neighbourhood - these can be VERY bright!
There is now also a "prototype" version of "Heavens Above" which is designed specifically for Mobile Devices - access it from your phone or tablet here: http://www.heavens-above.com/mobile
Now there's no longer any need to print out your satellite-pass charts and tables before heading outside for a spot of spacecraft-spotting - just take your phone / tablet with you, and get real-time tables and charts on demand.
The main features are as follows:
- "Live sky" chart will show you all the current visible satellites as they move across the sky. This is probably the most convenient display for an evening's viewing, as no navigation between pages is necessary.
- Predictions include all visible satellites up to a configured magnitude cutoff, plus Iridium flares.
- Location can be obtained from the phone itself using the HTML5 geolocation service.
- The site is implemented as a single HTML file and so transitions between pages do not require fetching data from the server.
- Runs on any device with an HTML5 capable browser (most modern Android and iOS devices).
- Makes use of the jQuery Mobile framework for a consistent "look and feel".
- Pages are currently optimised for the smart phone format, but can also be used on tablets. A tablet-optimised layout will be available shortly.
- The first version of the prototype is only available in the English language, but other languages will follow.