What are you looking for exactly? There's a lot of stuff that can be done right out of the box with DNN with little or no programming needed. Have you had a chance to look up the documentation yet?

Sanjay

If you want to use Paypal, you can use DNN out of the box without any code customization. There are various commercial e-commerce modules available from Snowcovered.com (largest repository of modules for DNN) which can offer credit cards, etc...
Someone else might chime in with regards to rosters/team management. If memory serves me right, a while back someone was trying to do something similar and maybe he/she might be willing to share that with you.
There is an events module which does the calendaring capabilities and there is an awesome repository module that offers a lot more capabilities than just a photo gallery.
Not sure what you mean by inbox - is this some type of email functionality or each user should have his/her own customized home page?

With regards to snowcovered.com - a word of caution. There are a LOT of commerically available modules. Before you jump in and start purchasing modules, please read up on the authors as well as the modules themselves. Some of them will work with only specific versions of DNN and others might not have been upgraded to the latest version of DNN available (at this time 4.4.1). In general, there are great modules out there on snowcovered.com supported by good authors who will stand by their product, but occassionally you will find the one or two that do not meet the standard.

Feel free to post on these forums too about any questions you may have about a product or feature of DNN. There are enough of us who troll the forums regularly and can offer advice/comments regarding what you're doing.
Sanjay