If you feel the app is useful, there are a myriad of sites out there who may be willing to review your app (Phandroid, Android & Me, etc) which is a good place

If you feel the app is useful, there are a myriad of sites out there who may be willing to review your app (Phandroid, Android & Me, etc) which is a good place to start. Other sites related to site administration might also be good to talk to. If the tool is free, you could also promote it via it's own website or blog and allow users to download the APK, or give them a QRCode on the site that allows them to get ti directly from the market using the barcode scanner tool