Nope, there is not. For GBA emulation you need the hardware for it, it can't be emulated via a Slot-1 cart

What about the DSTWO?

Apart from the DSTWO ofcourse, but that has additional hardware

im still asking myself why its impossible to make dstt software that allows GBA simulation
can someone explain that?

From what I understand it's simply the fact that the DSTT doesn't have the hardware required to run GBA games. That's why you can only do it with 1) the additional Slot-2 expansion or 2) a DSTWO flash cart, which contains the required hardware itself. The reason that the DS can run GBA carts is because the required hardware is within the GBA cart itself, but it leads many people (including me) to believe that a DS should be able to run GBA ROMs.
I was just wondering if someone may have found some sort of workaround to this problem, but it appears not.

Ah well, not too much of a problem. At least I can still play GB/GBC games with Lameboy  

Well, someone started a project for a GBA emulator for 'normal' flashcards about a year ago (possibly more), but there was talk of viruses and shit and it only ran at a couple of fps so not really worth anyone's time. Maybe that changed, though, so here's the links you need if you're interested:
https://github.com/ichfly/gbaemu4DS
http://ichfly.github.com/gbaemu4DS/

Love your avatar btw, World of Goo is brilliant.

Sweet, I'll give it a shot. Just the fact that someone tried is awesome.

And thanks! The original is actually a dancing Mario:



But I edited it to make it a dancing Goo Ball. By the way, not trying to spam or anything, but you might like to take a gander at GooFans, a WoG fansite. I'm a mod there so obviously I need to promote it as much as possible  

too bad its only desinged for R4 atm
doesnt work on my dstt even with homebrew loader

Same here. I even recall the emu mentioning something about DSTT not working  

Still, nice to see some effort on this front. Looks like it's well under progress, so someday it might support DSTT.