If you watch the top players serve, one thing you'll notice is that the vast majority of them serve various types of forehand pendulum serves mostly from the backhand side. There's a reason for this - it puts them in a better position for the next shot, especially if they want to favor the forehand if they get a weak return. It also allows them to get used to a limited number of returns - if they serve from the forehand side, they have to get used to returns that come at them differently. But players do this so mind-numbingly often that receivers are used to this type of serving. (Some top players do use tomahawk or even backhand serves from the forehand side, but these are relatively rare.)

A few years ago Baltimore Orioles star shortstop J.J. Hardy visited the Maryland Table Tennis Center. He was probably the best table tennis player in non-table tennis professional sports, at least in the U.S. - about 1850-1900 level. He had strong shots from both wings, but had one very unorthodox thing - his best serve was a forehand pendulum serve from the forehand side. Against MDTTC players, over and over they struggled with this serve since they had literally never seen it coming at them from this angle before! The ultimate test was when J.J. played against a 2400 player - and he struggled with the serve as well. As he put it, "I've never seen anyone serve that serve from the forehand side."

There are a number of advantages of serving from the forehand side. Here's a listing. (For this, I'm assuming both players are righties or both lefties.)

1. It forces the receiver to adjust to a serve he rarely sees.
2. It gives an angle into the short forehand, so that you can serve there and force an opponent with a good backhand flip to receive forehand. If you serve short to the forehand from the backhand side, there's no angle, and so the receiver can just reach over and flip with the backhand. If a receiver tries to "cheat" and move over to receive backhand, you can serve quick down the line and catch him out of position.
3. Against players below the top levels, many players can't receive effectively down the line against a serve short to the forehand. And so you can serve from the forehand side short to the forehand and then just camp out on that side, following your serve up with a big forehand.
4. If you are a strong two-winged player, the serve leaves you in perfect position to follow the serve up from both wings, depending on the return.
5. A tomahawk serve from the forehand side that breaks wide to the receiver's forehand, but goes off the side of the table so that the table is in the way of the receiver, is an extremely effective serve. It's very hard to loop, since the table is in the way. Lefties do this all the time to righties, serving forehand pendulum serves from their backhands that break outside the righties forehand side, with the table in the way. The serve can be effective even if done very deep. Because it breaks away from the receiver, he tends to reach for the ball, causing two problems - first, he loses control as he lunges for the ball, and second, he tends to lower his racket as he reaches, and so lifts the ball off the end.

So why not take a couple steps over and experiment with these serves? And if they work for you, then that's one more tool in your tactical toolbox.