I have been doing some homework...specifically n900 in mind..

#1 -looking into tweaking gtkgep ...



...so the interface is easier on the eye on the n900, and seeing if setting up new presets is going to be an easy thing, hard or impossible.



#2 -I would prefer something like the old jesusonic ...



, that is by default, built so one can easily write one's own effects...making it a VERY versatile option.
There being no source of the prog, I have hunted . only a tar ...doesn't help though.
BUT it may work on the n900 under specific circumstances ...*


#3 -took a run through on the new open sauce implementation of jesusonic for linux... JSUSFX...
So there IS a linux variant of jesusonic kinda sorta
(https://github.com/asb2m10/jsusfx)



which is pretty freakin' cool...
check out this demo vid.

https://www.youtube.com/watch?v=7f9fOeBecaY

and wondering if the n900 could handle it ..

and lastly...

#4 -revisited and did some digging on ecamegapedal...



(which is a hell of a program, I would put in 2nd behind jesusonic for versatility.)
it can handle ladspa plugins as well as the 30 presets it has...(I think presets can be written for it as well...)
I found a few things that make this a very viable possibility ..for the n900 at least.
firstly is there is an armel of it.
http://archive.debian.org/debian/poo.../ecamegapedal/
and secondly, primary dep for it is ecasound, which runs well in easy deb from what has been mentioned in one of the threads here.
So quite possibly the armel may be suitable or quasi suitable and possibly an armel of ecasound may be doable to make it run under fremantle proper.
Failing that, it is possible that since ecasound 2.7.0 already is stated as running fine in easy deb on the n900, and so the primary dep satisfied, then quite likely ecamegapedal will work with little to no problem if installed and run in easy deb on the n900.
But it bodes well if ecasound already runs well on the n900, then there is a very real possibility ecamegapedal will as well.
And a "maybe" ....that the program could run native-ly on the n900.

I forgot to mention Freqtweak which is also a helluva program...
enabling real time effects processing by altering the visually outputted audio spectral manipulation of the sound...
Wicked cool...




FeqTweak is one of the most likely candidates for the n900 since it is still in the current debian and buntu standard repos...
So it may well work pumping it through Leste.

* and naturally , again extrapolating on this same tack, it may also be possible for the old (doubtful about the newer JSUSFX) jesusonic tar to install and run fine under Easy Deb.

Of course these options are theoretical at this point.