I just published bLogcat at Google Play store.
You can find it here: https://play.google.com/store/apps/details?id=jhu.cs.hinrg.blogcat
Or search "bLogcat".
It is a logcat tool running silently as a background service. Comparing with other current tools, bLogcat can record all types of logs in Android simultaneously. For example, you can trace main, radio, and events at the same time. After you stop the tool, the traces will store at sdcard/logcat for you to do offline analysis.
BTW, for Jelly Bean users, all logcat tool works only in debug mode, which means you need to connect your phone with PC and input
adb shell pm jhu.cs.hinrg.blogcat android.permission.READ_LOGS