Monochrome graphics

I have built a microcontroller based weather station that downloads and decodes METAR and TAF data directly from the internet and displays it in readable form on a text LCD screen.
I would now like to take this one step further and use a graphical LCD screen as readout, displaying weather situations with icons in combination with text.
The thing is, the screen that I have available is a monochrome graphic type (pixels can be on or off with no gradients in between) and the resolution of the display is 240x128 pixels. I have seen a lot of beautiful icons on the web but all are fancy graphics that are not suitable for my display.
To give an idea of what I need, here’s a screen shot of a prototype windows program I once wrote:

The icons used here are based on the ones shown on this page:

They are OK, but a little fancier and larger would be nice (resolution up to 64x64 pixels).

If you understand Dutch, here’s a little description of my project, including some pictures: