You alone must decide what your career goals and needs are. The problem is, there is no real way of measuring how much you can expect your income to go up as a result of any given certification. It also depends on non-related job search skills such as how well you network.
Lotus is one of the early kings of PC software.
It is no longer the spreadsheet king and its word processor, Ami Pro, has lost the competition to Microsoft Word. However Lotus is still powerful. Its two top products are Lotus Notes, which allows business employees to collaborate in real time on products, and Lotus Domino for developing web sites. Lotus currently has three levels of software certification. The second and third levels advance beyond that, into application development.