A worldcat link may be found here (Staff and students of Groningen log in with p-or s-number).
This is absolutely the first place to go to find new inscriptions. Supplementum Epigraphicum Graecum (SEG) is an annual survey, collecting newly published Greek inscriptions and studies of previously known documents. New texts are normally reproduced with a critical apparatus, and brief comments. Texts that are published in epigraphical corpora repertoria and are not normally reproduced in their entirety.
Each issue contains the harvest of a single year, with a delay of a few years: for example, the issue of SEG published in 2005 contained all inscriptions published in 2001.The texts are arranged geographically according to the order of Inscriptiones Graecae. After that follow Asia Minor, Syria, Paleastina, Arabia, Egypt, Nubia, and Kyrenaika, with the cities listed in alphabetic order. For each place the texts are listed in chronological order, according to 4 categories: public documents, dedications, epitaphs, miscellaneous. Inscriptions with an unknown provenance are discssed separately. A very useful section Varia discusses epigraphic bibliography on various topics.
The volumes have extensive and excellent Indices: Names of men and Women, Kings and dynasts, Roman emperors, Geographical Names incl. Attic tribes, demes etc.; Religious Terms; Military Terms; Important Greek words; Selected topics (Eglish); Concordances to IG and other major corpora and SEG volumes, as well as a list of abbreviations. There are also separate index volumes available.
SEG covers the entire Greek world, although material later than the 8th century A.D. is not included. Each issue contains the harvest of a single year, with a delay of a few years: for example, the issue of SEG published in 2005 contained all inscriptions published in 2001. The current editors of SEG are: A. Chaniotis, T. Corsten, N. Papazakardas and R.A.Tybout.
For more information: http://hum.leiden.edu/history/research/projects-umw/seg.htm
Since 2021 SEG is available via Brill scholarly editions, on a subscription basis (all following *links assume access via the University Library of Groningen). The homepage can be found *here. It offers extensive search possibilities: a link can be found *here; instructions for the search possibilities can be found *here. Indexs can be found *here. Search optionas are not quite intuitive, so you may need to practice.
An older digitised version of SEG has been on-line since 2009. For instructions on how to use this version click *here. There is also an instruction movie at Youtube. You can sort the results of your search by relevance or publication date. If you only look for inscriptions you will probably want to disable an automatic search in other other Brill on-line publications.