It is indeed a good idea. But do be sure to send it to a unit that wants small sizes. I have seen some complaints in AnySoldier posts about travel sized items they have received and did not want. Other units request them.
Also, be very sure to sort through all of your donations to be certain that what is eventually packed and sent is fresh, unopened and has never been used. You would be surprised by what some people donate. I gathered tons - literally - of goods for Katrina victims and was horrified by some of what was dropped off, both in terms of clothing and in personal care items. I had no idea how many people had large collections of products they had taken from hotels until they started to drop by to give them to us. The unfortunate part was, so much was partially used.
Nobody wants half empty bottles of hotel mouthwash, unwrapped and used travel sized toothbrushes or small tubes of toothpaste. And, they certainly don't want bars of soap that have been used by someone else, no matter how lovely smelling or costly. Yet I was given a lot of just such things by the nicest looking people. What were they thinking?