By coincidence I've been fooling around with dry-transfer lettering on a ship model recently. I'll second Ed's endorsement of Woodland Scenics. The company makes quite a broad assortment of dry-transfer products, ranging from alphabets to railroad logos to old-fashioned gasoline ads. It has its own website, and sells directly to consumers: http://www.woodlandscenics.com/ . (Disclaimer: I haven't ordered anything from that site over the web; I managed to find the lettering I needed at my "local" hobby shop - which is about thirty-five miles away.)
In my experience, Woodland Scenics dry transfers work quite well. They transfer easily from the sheets, burnish down nicely, and are beautifully printed. My one complaint about the generic alphabets centers around the way they're packaged. In any one envelope (which costs somewhere in the neighborhood of $5.00) you get one small sheet with several sizes of lettering on it. In plenty of applications, that comes in handy: you may well find yourself wanting to make ship names in several sizes, each requiring only a few letters. But if you want to put a name with two L's in it on each side of the ship, you've got a problem: each alphabet on the sheet contains three L's, and you need four. That can be particularly awkward if you don't notice the shortage before you leave the hobby shop (or place your order over the web).
Also - if you need numerals in addition to letters, you have to buy another sheet. Woodland Scenics packages letters and numerals separately. [Later edit: I need to correct myself here. I took a look at a couple of Woodland Scenics sheets in my workshop. The alphabet sheets do include a modest assortment of numerals - but not many.]
Another possible source is Microscale, which makes quite a few excellent sheets of waterslide decal alphabets: http://www.microscale.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=ALPHA . These sheets are considerably bigger, and each has literally hundreds of letters and numbers on it.
The dry transfer and the waterslide decal both have advantages and drawbacks. In many situations the dry transfer is easier and quicker, and gives a neater result. On the other hand, the waterslide decal can be moved around on the surface after it's applied - and modern waterslides, used in combination with the various softening and setting solutions (e.g., MicroSol and MicroSet), can be applied in such a way that the carrier film is, to all intents and purposes, invisible.
Hope that helps a little. Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.