Fantabbo!
My voice isn't too high, but... Not too low either. I've been practising making my singing voice lower and that's worked for me. If I can sing lower then obviously I can speak a bit lower as well.
The only thing is that if I were to sing it would give me completely away. You can't fake a manly singing voice, and I'm a musician so it's gonna be really tough in that respect.
But to sing lower (which is easier because you can actually tell what the relative pitch is) I just put on CDs with songs that were a bit too low for me (David Bowie, Billy Joel, etc.) and tried my damndest to sing the low notes as loud as I could (your voice goes quieter the lower it gets), and did it every single day. I drive a lot for work so it was easy to just sing away in the car.
I've always been able to sing fairly low, to about a bass E without hardly any trouble at all. But I did have a bit of difficulty hitting a D and C. Now I can hit them pretty regularly without too much strain (be careful not to damage your voice, eh?) I've been able to get down to a Bb (and on days where I went to a concert or sports match the day before and screamed a lot I've actually got down to an F below bass C.)
I find that if I'm having a low voice day and take advantage of it it helps. If I stay up really late at night the voice goes deeper so I sing as much as I can late at night and it helps.
But if you're not a singer, I don't know how to help you
And, I did have some fun. Went parasailing and jetskiing.