swype for eris is the only way to go IMO. Google it and watch the video to see what its all about before you download. BTW, there are two versions out now, one that is approx 2mb and one that is approx 7mb. The larger file has more options and is overall better IMO. Search Swype HVGA.apk for the download.
Ive heard some goopd things about swype, its very good for one hand typeing. but ive also heard good thngs about the "better keyboard" app. You have two very good choices my friend.
No not that I have ever heard of.....I love Better Keyboard, but I can't say anything about how it works on the Eris...it might not even be available on the Eris if the app is made for only versions higher than what the Eris has ya know? Just tell your wife to do a search in the Market for keyboards...whatever will work for the Eris will show up