Multi MOSFET IC for Controlling 12V LED strips with Arduino

Assuming you can get by with a common Source connection (typical for an LED driver), you might be able to use the SLA5085 which is 5 MOSFET N-channel array:

with the following specs:

Vds: 60v

Id: 3A typical, max 10A

Vgs: 3v @ Id = 3A

It is available from Digi-Key.

Edit: Changed to more appropriate type of MOSFET

Rather than those huge olde style packages, how about considering a modern dual that would take up little space, such as the AON7804

These little guys are 26m\$\Omega\$ (max) with 4.5V drive and are only 3mm x 3mm. Also, only 34 cents each in 25's, so all 6 will be about a dollar.

If you want to use a relatively large package such as SO-8, they're also available though not quite as high performance, but almost as low price, and should be more than okay for your application (and they're easy to solder with 50 mil pitch and no thermal pad beneath- so not as good heatsinking, but easier). The DMG9926USD should do nicely.