You should get information about the USB controller with cat /proc/pci and about USB devices with cat /proc/bus/usb/devices.
Newer laptops come equipped with the Universal Serial Bus - USB. The following USB devices are available, not all of them are fully supported by Linux yet: keyboard, mouse, printer, tablet, camera, cpia, webcam, MP3 player, modem, wireless LAN, audio, jukebox, scanner, storage (hard drive, memory stick), floppydrive, ZIP, Super Disk - LS 120, compact flash reader, CD, BlueTooth, ethernet, serial, joystick, USB Host-to-Host Cable, hub .
Please note, I have got a report that the power by a laptop via USB is not enough for some kind of devices, e.g. Web Cams or hard disks. But it seems to depend on the laptop and the specific device. With desktop Linux machines these USB devices work flawlessly, but with mobile devices not.