A fundamental thing when developing Android apps but also in general when developing with device emulators is to test your app on real devices. Android makes this easy. By activating "USB debugging" on the device and connecting it to your workstation with an USB cable. The app can then either be started from within Eclipse or by deploying it using the adb bridge.However, most often I do not really want to debug the code on the real device, but rather just to test it by running it. ADB doesn't however allow you to install your app to an arbitrary IP (in the WLAN net for instance), but just by using the USB cable which, however, is really annoying when you just need to deploy your app. But don't give up, there are some alternatives which allow you to have some kind of OTA installation.
As a prerequisite for using one of the below mentioned approaches you have to allow the installation from non-market sources which you can do in the "Settings > Applications"
Installation over E-Mail
The probably most simple approach for installing your app is to send the APK file to your own email address. Then you open your email (i.e. Gmail) inbox on your Android device and click on the attached APK file. This will automatically launch the according installation.
The drawback: a lot of emails you send to yourself which clutter up your inbox. Though, it might be useful when you want to send the app to some of your friends for testing purposes.
Deploy on some website
Alternatively you may have some hosting space somewhere. In such a case what you may do is to create a simple HTML page showing a "Download app" link which starts the download of your APK file (which you deployed on the server). To speed up a bit, you could use the Chrome-to-phone extension for pushing the page to your mobile, or you could create a QR code pointing to your deployed APK file and scan that from your mobile.
Although by having a FTP connection to your webspace you may be quite fast in deploying a new version of your app, this whole process is still quite tedious. Moreover it may not be granted that you have a webspace :)
Currently my favorite is Dropbox. Link it with your computer, create a folder and copy your APK file there. Then you open up Dropbox by using the mobile Android app, go to the same folder you just copied the file and click on it to install. Easy, huh :)
Moreover you can also use the approach of having a simple HTML page. Just copy that in the Public Dropbox folder and get the according public URL.
If you don't have Dropbox you can click here to create an account and get 250 MB of additional storage for free.