I'm kind of surprised how many people seem to think they need a 3dfx card but don't have any specific games in mind. Not to be an ass but I've noticed it multiple times.
You're looking at a pretty narrow time period, 1997/98.
For some games you're stuck with either Glide or software rendering, however for some of them software is fine. Blood is an example.
For some games D3D or OpenGL support have improved since 1998. Unreal at release was best played with a 3dfx card, but eventually they updated the D3D renderer and there's also improved renderers you can download for use on modern systems.
For a period of time 3dfx cards were the best/most compatible, but that was even true for non-glide games. For those games it's a gamble whether their early use of e.g. D3D looks fine on a modern card and a 3dfx card might be the thing they work best with.
In any case the Voodoo cards will limit the resolution and color depth compared to what you can play on with your gf4.
In any case here's some games I played with Glide back in the day: Unreal, Deus Ex, Carmageddon, Blood, Shadow Warrior, GTA, POD.