liblzg is a minimal implementation of an LZ77 class compression library. The main characteristic of the library is that the decoding routine is very simple, fast and requires no memory.
AGfUPX is a nice GUI for UPX with many advantages. Selecting a file using drag & drop, shell integration (adding "Open with AGfUPX" option to the context menu of exe/dll files) and redirecting UPX output to a windows dialog box are only few of them.