I know that Multipanel in LevelScheme can probably let you do what you want - but I don't have much experience with it and the examples in the docs are fairly sparse.
I've already pasted one of the examples into this SO answer, so have a look there and see what you think!
Here's my attempt with GraphicsGrid.
The thing that Multipanel lets you do but GraphicsGrid doesn't
is to let you use varying Column/Row sizes.
This means that I struggled to get the arrows drawn in programmatically, and resorted to hand drawing them using the "Drawing Tools" panel ( :D )
With[{yslice1 = .5, yslice2 = -.8},
GraphicsGrid[
{{DensityPlot[Sin[15 x y], {x, -1, 1}, {y, -1, 1},
ColorFunction -> "PlumColors", AspectRatio -> 2,
Epilog -> {Dashed, White, Line[{{-1, yslice1}, {1, yslice1}}],
Line[{{-1, yslice2}, {1, yslice2}}]}],
Plot[Sin[15 x yslice1], {x, -1, 1}, Axes -> False, Frame -> True]},
{SpanFromAbove,
Plot[Sin[15 x yslice2], {x, -1, 1}, Axes -> False,
Frame -> True]}},
Spacings -> {Scaled[0.2], Scaled[0.0]}]]

Edit:
Here's the same thing using LevelScheme, note that the frames line up.
It should be possible to add arrows - since LevelScheme has lots of new arrow directives - but I'll leave that as a homework problem!
<< "LevelScheme`"
{yslice1 = .5, yslice2 = -.8};
Figure[{
SetOptions[Multipanel,
ShowTickLabels -> {True, False, False, True}, Background -> Wheat,
PanelLetterFontSize -> 10, Margin -> {{40, 40}, {40, 0}}],
Multipanel[{{0, 1}, {0, 1}}, {2, 2},
XPlotRanges -> {-1, 1}, YPlotRanges -> {-1, 1},
XFrameLabels -> textit["x"], YFrameLabels -> textit["y"],
TickFontSize -> 10, XFrameTicks -> LinTicks[-1, 1, .5, 4],
YFrameTicks -> LinTicks[-1, 1, .5, 4],
BufferL -> 1.5, BufferB -> 3, Order -> Vertical,
XPanelSizes -> {1, 1}, XGapSizes -> 0.25, YGapSizes -> 0.2],
FigurePanel[{1, 2}],
RawGraphics[
Plot[Sin[15 x yslice1], {x, -1, 1}, Axes -> False, Frame -> True]],
FigurePanel[{2, 2}],
RawGraphics[
Plot[Sin[15 x yslice2], {x, -1, 1}, Axes -> False, Frame -> True]],
FigurePanel[{2, 1}, PanelAdjustments -> {{0, 0}, {0, +1.2}}],
RawGraphics[
DensityPlot[Sin[15 x y], {x, -1, 1}, {y, -1, 1},
ColorFunction -> "PlumColors", AspectRatio -> 2],
Graphics[{Dashed, Thick, White,
Line[{{-1, yslice1}, {1, yslice1}}],
Line[{{-1, yslice2}, {1, yslice2}}]}]]},
PlotRange -> {{0, 1}, {0, 1}}, ImageSize -> 2*72*{5, 3}
]
