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While this series is a little too fever pitched for the casual anime fan, DiGi Charat is cute, and even sillier than the Mini-Goddesses. Be careful though, you'll definitely need basic knowledge of Japanese culture to understand most of it.
If DBZ replaced insane alien superpowers with katanas and turned the maturity up just a notch, you'd get Kenshin. It's not quite that simple, but it's definitely got the violence that any DBZ fan wants.
There's not nearly the fanservice, but the typical guy who would enjoy Nanako's bouncing would also find Onizuka's badasseries to be entertaining as well. It may not be all you want, but it might teach your pervert friend that anime can be pretty cool without naked girls in it.
If you're watching Nanako, it's obvious that you want fanservice. This will cater to your ecchi whims. Careful, many places demand ID to buy this one. The maturity level should be self-evident (Read:Nonexistent but old enough anyway)
This takes the maturity control and turns it up a lot. If you have a secret desire to see lots of violence and killing, but can't take the simplistic storyline of DBZ, this could very well be your next favorite. I don't suggest this anime to anyone under 13 though, due to more complex plot and much more graphic violence.
If you want robot-girl anime with good animation and story without the CLAMP influence, this is one for you. SMJ has a lot more action as well, while raising many of the questions seen in Chobits.