I've tried many things to get my bandmates (in both bands that I'm currently in) to sort of lose their inhibitions and actually get into the music we play, because with that we'll have a better stage presence. Are there any tips for this?
Drugs and Alcohol.

But seriously, hopefully it'll come with experience!
Quite impressive for a cripple.
Do you notice this during live gigs, or is it just during rehearsals?
Are they not confident in the playing the music?

You might find the more gigs you do, things will get better. If not, you might need to look at freshening up your repertoire, or looking for a new band. You have to enjoy what you're doing!
I can't really give you any tips on getting your other bandmates into it but I will say this.
As someone in the crowd: If the band isn't headbanging, I'm not headbanging. Same goes for every genre. If the band isn't into what they're doing, the crowd certainly isn't going to be.
..I was watching my death.
Maybe they need to be a bit more comfortable with the material they are playing before they can groove out? I.e. is more practice required?
Quote by AlanHB
It's the same as all other harmony. Surround yourself with skulls and candles if it helps.
A few people have hit on this, but stage presence really comes with experience and goes hand in hand with being comfortable and confident. The best way to gain confidence and comfort is to make sure everyone in the band is very practiced up on the songs and can play them effortlessly.

Audiences can have an impact on stage presence as well. I think there's a give-and-take of energy that goes on between crowd and performer. Of course, having a good stage presence is easier when there's a good, energetic crowd watching you. However, as everyone who's been in a gigging band knows, not every show is going to have an enthusiastic crowd, or in some cases much of a crowd at all. In those situations you have to be able to spark the energy from the stage. If you're having a good time, the audience is much more likely to enjoy the show too.
Quote by Zeppelin71
Umm. . .uh. . .your mom touched sjones' dick. YOUR MOM TOUCHED OUR GUITARISTS GENITALS IN A CAMPER AT A BIKER FESTIVAL! truth.
Can I just ask what kind of music you play? I'm in a metal band and stage presence is a HUGE thing for me. You basically need to practice your whole set with stage 'moves' at home, and be able to completely rock out by yourself. Once you can do that AND be able to play as perfect as possible, it's just conquering any shyness or self-consciousness you have. That comes with time, but can be speeded up with alcohol Haha. I personally drink a bit before I play, so I'm feeling confident but my playing isn't effected. If you do all that you should be fine! Unless your band are just boring and don't actually want to have any stage 'presence'.
I second, third? the idea of being very comfortable playing the songs. You need to be able to play them in your sleep before you can start doing other things and take your attention off playing for a period of time. Can I ask how many gigs you've played? And how are your bandmates before the gig? The more you are comfortable playing on stage the more loose you can be on stage. But no matter what some people just don't have that stage presence gene. My guitar player almost never moves, but if you bring it up with him he'll claim he was moving?
Timbit2006 hit it dead center. If You arent moving, the crowds not moving. You might as well supply lawn chairs and travel pillows for the crowd, b/c your performance is boring. Something simple i like to call 'filling up the gas tank', involves making random trips to see your drummer, and headbang with him, throughout your performance. Watch any Professional Live Concert footage and you'll see members of the band do this. Try this first, and progess to cordinated jumps and headbanging as a band. Stage Presence is EVERYTHING!
Agreed with everyone else. First comes absolute comfort playing the songs you are supposed to play. Your first goal is to get everyone to that point, and then to make sure that you guys are having fun with it.

Don't try to have stage presence, yet. Just have fun up there. Once you're at a place where you guys can have fun playing, start making a point to make more eye contact with the crowd while still having fun up there.

Baby steps. How experienced are you guys?