If you are looking for the ultimate stumbling card for your laptop to replace that venerable Senao 200 mW PCMCIA card, I believe the Ubiquiti SRC may be it.
With up to 300 mW transmit power, excellent receive sensitivity, MMCX antenna connectors, operation at 2.4 GHz and 5.8 GHz and a well supported chipset in Linux it may be the perfect all-round stumbling/wardriving card.
Chipset
Atheros 5004
Radio Operation
802.11 a/b/g
Interface
32-bit Cardbus Type III
External antenna ports
Dual MMCX
2.4 GHz TX/RX Specifications
802.11b
1 MBps 24 dBm / -96 dBm
2 MBps 24 dBm / -95 dBm
5.5 MBps 24 dBm / -94 dBm
11 MBps 24 dBm / -91 dBm
802.11g OFDM
6 MBps 24 dBm / -94 dBm
9 MBps 24 dBm / -93 dBm
12 MBps 24 dBm / -91 dBm
18 MBps 24 dBm / -90 dBm
24 MBps 24 dBm / -86 dBm
36 MBps 23 dBm / -83 dBm
48 MBps 22 dBm / -77 dBm
54 MBps 20 dBm / -74 dBm
5.8 GHz TX/RX Specifications
802.11a OFDM
6 MBps 20 dBm / -94 dBm
9 MBps 20 dBm / -93 dBm
12 MBps 20 dBm / -91 dBm
18 MBps 20 dBm / -90 dBm
24 MBps 20 dBm / -86 dBm
36 MBps 19 dBm / -83 dBm
48 MBps 18 dBm / -77 dBm
54 MBps 17 dBm / -74 dBm