Neverball is a freeware PC game that has been ported over to the Dreamcast and released over at DCemu, and is essentially a Super Monkey ball clone, which is great as if the Dreamcast lasted just a year or two longer it may of got that game. It is a beta so it isn't quite perfect yet: for example the ball which should looks like it does in these screenshots looks more like a ball made of bubble paper and sometimes when there are a lot of objects on the screen things can disappear(though I believe this only happens if you have the polygon settings to high). Still, there isn't many 3D homebrew games about and for what it is it looks the part.
What really makes this worth playing though is how additing it is. There are two games on the disc: Neverball is the Monkey Ball style game where you must collect a certain amount of coins and reach the exit before the time runs out. Just like that game you can fall off the stage and you only start with three lives, but can gain more by collecting lots of coins. You unlock the stages as you beat them, and luckily there is a VMU save state feature, as well as a replay save feature if you want to re-watch a skillful round. There are three sets of stages on the disc, including a set of harder ones all alphabet shaped!
The 2nd game Neverputt takes the same physics and apples them to a crazy golf game. If you ever played the highly additive golf game in the otherwise average 101 Dalmatians game on the DC it plays a whole lot like that, only the stages get just as surreal and topsy turvy as the Neverball stages, with teleporters and traps. Again theres three sets of difficulty stages, and it's great fun.

So if you're looking for something a little different to Beats of Rage mods and first person shooter ports this is a neat little game to pass the time with. It has some sweet MOD tunes as well. This is the only video of the Dreamcast version I could find online (being played terribly), but I might rip some footage myself at some point.