http://uregina.ca/~myers20s/mario%20html/features.html
Someone linked to this site on Gamefaqs and it's awesome. Basically, it has descriptions and pictures of every SMB3 (GBA) e-reader level from both Japan and the US (including lvls not released here yet). It also has a download with the japanese levels converted to printable dotcodes that you can scan into the e-reader and use in the US version! I don't have my e-reader here (or a second GBA) to try this but it looks pretty freakin cool.
Those extra levels that look like the original Super Mario Bros game look neat 😉
I still haven't gotten SMA4. I may in the future though - I own the original SMB3 for the NES, but I never completely beat it all the way through, and I'd like to do that eventually. The extra stuff you get with those e-reader cards looks neat, but it costs a good bit of money to buy an e-reader and all those sets (I have a second GBA and link cable alreday).
I guess that site also has save states with the e-reader levels on it so I tried some of them out.. Very fun, although it's not the same on a keyboard 😃
I tried those codes. They dont seem to work for me. What I am going to do is borrow someones gameshark, and use the sharkport save.