A couple of useful plugins

[Lukasz]

Helicharly's ATC

http://forums.x-plane.org/index.php?showtopic=38194

Just like default ATC simulation from FS9 Speech synthesis is like it is in X-Plane, so don't expect nice recorded voices, but still it enchances long (and short) IFR flights considerably. Ask for startup and taxi, get guidance and vectors along the way, clearance to land and much more other nice features.

Pilot View by Sandy Barbour

http://www.xpluginsdk.org/pilot_view.htm

I've found native X-Plane TrackIR support "unserviceable" but this little plugin helped me big time with setting up my virtual head. You can have different setup for every aircraft you have, as well as place your viewpoint anywhere inside or outside of the aircraft and then save these viewpoints for further use.

Saitek X52 Pro MFD by DMARC0815

http://forums.x-plane.org/index.php?app=downloads&showfile=8076

It displays IAS, alt and vs on the throttle's MFD, but what's the most important, it's the possibility to tune your COM and NAV radios by using buttons and knobs on the throttle itself. It's really helpful for some virtual cockpit equipped aircraft and much cheaper that buying separate radio panel.

Airport Navigator by Jens Ansorg

http://forums.x-plane.org/index.php?autocom=downloads&showfile=4930

Shows transparent layout of the airport you're currently in. No more looking on "local map" or wandering around, while searching for that 23R runway, you were supposed to take off from 20 minutes ago Another feature is the ability to show you, what is the closest airport, in case of en-route problems, as well as what are the runways on that airport, so you know how to set up for landing approach.

[MdMax]

VisualAltimeter 1.0 by snailpup

http://forums.x-plane.org/index.php?app=downloads&showfile=2458

It's just a great tool for some panels where it's hard to read the altimeter setting or if you don't want to loose time zooming on your gauges while flying.

[sede]

Field-of-view per Aircraft Plugin v1.2.2 by Jens Ansorg

It enables to assign Field-of-view (FOV) setting per aircraft. It stores FOV setting for three different views.

For Linux, Windows and OS X universal

http://forums.x-plane.org/index.php?app=downloads&showfile=4455