Does anyone have a suggestion for a small plugin I can make?

[Deckhead]

I would like to contribute to Code::Blocks, but having never contributed to a project before, I think tackling the main app might be a problem for me.

So I would like to start with a small plugin first to learn how it works and to do something I could handle. I would prefer it not to be a toy plugin, but something useful.

I use Dr Memory a lot, so I thought something that calls DrMemory and parses the results, and potentially highlights / jumps to code where the allocations leak etc. But I have no idea how much I'm biting off there.

[oBFusCATed]

You can inspect the code of the valgrind plugin.
It probably does something similar to what you want to do.
Generally it is better to extend plugins instead of duplicating them.

[ollydbg]

I would like to contribute to Code::Blocks, but having never contributed to a project before, I think tackling the main app might be a problem for me.

Good to hear!
As oBFusCATed said, I think the valgrind plugin is a small plugin which only communicates the valgrind with pipes. Also, there are some small plugins like CppCheck plugin, Cscope plugin.